THE SOFTWARE FOR PCR PRIMER'S SELECTION/ANALYSIS "PRIMER-MASTER 1.0"

 

     USER'S MANUAL

 

The program "PRIMER-MASTER 1.0" is designated for search and selection

of best primers and  formation  of  optimal  primer's  pairs  for  PCR

performance. The primers selected  by  program  maximally  satisfy  to

various requirements, providing high  specific  and  efficient  ampli-

fication, and may be used in broad range of application of PCR.

 

The program  has  two  main  variants  of  work  :  "Primer_test"  and

"Auto_search", which are presented in  main  menu  bar  as  two  first

items. The third item  "Utilities"  contains three little subprograms.

The first two of them have no independent significance but may prove to

be useful for work in main variants. The last subprogram "New sequence

type" allows to type-in and edit comfortably new nucleotide sequences.

 

     To enter some item of menu or option, press "Enter"-key, to leave

- press "Escape". To pass from  one  item  or  option  to  other,  use

"Arrow" - keys.  To  stop  the  work  of   program, press  "Pause". To

interrupt the work, press any  key  and  answer  in  positive  way  to

proposed questions.  To  leave  the  program  before  start  or  after

interruption, resort to QUIT option of the main menu or press Escape.

 

 

 <<<<<<<<<<<<<<<<<

 << AUTO_SEARCH <<

 <<<<<<<<<<<<<<<<<

 

     "Auto_search" implies automatical search and  selection  of  best

primers and formation of optimal primer's pairs for  PCR.  Working  in

this variant program  enables  to  treat  one  or  several  nucleotide

sequences  and  to  select  primers,  which  are  universal  for   all

considered sequences (regime Universal) or, on the contrary,  specific

for only one out of all sequences (regime Specific).

 

     SEQUENCES

Option "Sequences" allows to point out the names of  being  introduced

sequence-files.This option opens three active windows:

1)Upper string, indicating the path to current  directory  and  file's

pattern;

2)Left window, presenting files  of  current  directory  according  to

chosen pattern;

3) Right window, displaying chosen and introduced file-names.

The user may move along windows by means of Tab-key (or Tab+Shift - in

the opposite direction). Being in Upper string he may change path  and

file's pattern. Being in the left window  he  can  move  along  files,

change directory or drive (the last - by F2-key) and input  file-names

by means of pressing Enter, Space-bar or Insert keys.  User  can  also

view any file by means of F3-key  or erase any file from disk by means

of F8-key. Being in the right window he can delete file-names (Delete-

key) and point position for input of the next file. When all sequence-

files are introduced - press F10. If You have changed Your mind - press

Escape and all actions carried  out  in  this session will be abolished.

The number of treated sequences is up to 100 in this version of program.

The length of any sequence  is limited by about 65000  nucleotides. The

total length of introduced sequences is not limited. The maximal size

of viewable file is about 300K.

 

 

     SETTINGS

Option "Settings" contains directives essential for work of the

program. These directives may be changed by user.

 

   1) "Output file names" - allows to define the names of all  output-

files which may be formed if program works in variant "Auto_search".

  The first output file contains optimal pairs of primers. If no  name

is defined by user, the name "pairs."with  extension  corresponding to

number of program's start will be assigned (for example "pairs.025").

  The second file ( by default the name is "primers.XXX") contains the

best selected primers without pair's formation.

  The third file ( by default the name is "primall.XXX") involves  all

primers and some information about them.  This  file  is  formed  only

according to user's wish. In some cases this file may be very  useful,

especially for its employment in "Primer_ test"  -  so  You  can  make

primer's design actually in manual mode. The file may be  very  large,

so before assigning its formation please check availability enough space

on Your disk.

  The last output file (by default the name is "location.XXX") contains

localization of all selected  primers  on  all  considered  sequences.

Obviously this file will be formed only during the search of universal

primers for several sequences (regime Universal).

Note, if particular path for first output file  is  defined  by  user,

this path will be valid for all other output files. The extension of all

files equals the extension of file "pairs."

-----------------------------------------------------------------------

 

   2) "Number of parts" - number of parts the sequence is divided  in.

The division of sequences in some parts allows to avoid situation when

all primers for plus and minus chain are found in the same site and no

pairs can be formed. After division the best  primers  will  be  being

searched  within  every  part.  It  provides  pair's   formation   and

considerably accelerates program's work. The number of  parts  may  be

from 1 (the whole sequence) to 9.

 

   3) "Set of margin" - allows to  set  left  (  5')  and  right(  3')

boundaries on sequence and to restrict the fragment  where  search  of

primers  will be carried out. The restricted  by  boundaries  fragment

may be divided in some parts as it has been described above.

 

   4) "Sites for search" - allows to point the boundaries  of  up   to

20 sites of sequence, where primers are searched within.  The  defined

sites may not be divided in parts.

 

   5) "Amplify zone" - allows to select primers which will amplify certain

fragment of certain sequence (if working regime is Specific) or  amplify

respective fragments of all proposed sequences  (if  working  regime  is

Universal). In any case user must point the left (5') and  right  (  3')

boundaries of interesting fragment on the first sequence, and  the  best

primers will be being searched within close zones (  100  nucleotides  )

up- and down- stream of the fragment.

The last three items restrict in some way zones for primers  search  and

selection and any of them excludes all others.

------------------------------------------------------------------------

   6) "Length of primer" -  the  user  may  set  minimal  and  maximal

permissible length of primers (in range from 16 to 26 nucleotides).

During program's work this value may be changed  automatically  within

set limits in one or other  direction  depending  on  regime  of  work

(Specific or Universal) because it is reasonable to expect  more  long

primer to be more specific and more short primer to be more universal.

 

   7) "Size of ampl. fragment" - allows to set the desirable lower and

upper limit of size of flanked by primer's pairs fragment.

 

   8)  "Difference  of  tempr."  -  permissible   difference   between

annealing temperatures of primers sharing one pair.

 

   9) "Temperature limits" - allows to set permissible lower and upper

limits  for  annealing  temperature  of  primers.  Temperatures  are

determined by the nearest-neighbor method with taking into account the

nucleation  constant.  Temperatures are calculated  for PCR buffers of

0.05 M concentration of monovalent kationes. But in range from 0.025 M

to 0.075 M  these temperatures are also valid.

 

   10) "Save settings" - preservation of majority of directives, which

have been set in SETTINGS. If the  directives  are  not  saved,  their

values will be valid only during current work of program.

 

 

     As mentioned above automatical  search  and  selection  of  best

primers may be carried out in two regimes: "Specific" and "Universal".

 

     SPECIFIC

 

     Regime Specific allows to  obtain  pairs  of  primers,  providing

specific amplification of fragments of only  one  nucleotide  sequence

out of all proposed ones.

It must be noted, the name of sequence specific primers  are  searched

for ( treated sequence ), shall be pointed out as the first in  option

"Sequences". All primers will be tested in respect of their capability

of binding with non-specific places (false priming) on treated sequence

and on all other sequences, which names have been introduced after the 

name of treated sequence.

  "Dir. for spec.check" - the user may also define targets for check

of primers specificity by means of pointing the directory containing

these sequence-files.

  "Auto_margin" (switch On - Off  by  Enter  key)  -  this  regime  is

foreseen for the search of specific primers for one out of related and

probably sequenced  from  different  position  sequences. It allows to

align sequences approximately  and to avoid choice of primers to sites

of treated sequence, which are not presented in other ones.

 

 

     UNIVERSAL

 

     Regime "Universal" allows to obtain pairs of primers, which are

universal for all considered sequences.

Names of sequences must be pointed in option "Sequences" and the order

of introduction of names does not matter.

   Using "Sequences for spec.check", up to 100  additional  sequences,

which amplification is undesirable, may be introduced. The same may be

done by using option "Directory for spec.check" (the user  must  point

only directory containing unlimited number of such sequences). In both

cases the program works so that these sequences can not  be  amplified

in PCR with primers universal for main group of sequences.  To  cancel

settings made in "Sequences for spec.check" - enter  this  option  and

remove all file-names from right window or only press Escape.To cancel

settings made in "Directory for spec.check" - enter  this  option  and

press Escape. Since these two options exclude one other,  activity  in

any of them abolishes settings made in other option.

 

   Option "Difference of size" sets an maximal difference between  the

lengths of fragments of different sequences,  amplified  by  the  same

pair of primers.

 

========================================================================

 

 <<<<<<<<<<<<<<<<<

 << PRIMER_TEST <<

 <<<<<<<<<<<<<<<<<

 

     "Primer_test" - allows testing your oligonucleotide with  respect

to any sequence (using option "Test  on  sequences")  and/or  to  some

intrinsic properties of  the  oligonucleotide  it-self  (using  option

"Self-test").

     Option "Primer" allows to handle the oligonucleotides to be tested.

The user may type-in the sequence of oligonucleotide to be tested. Besides

the common symbols A, G, C and T, the ambiguous bases may be included,

according to the table belong:

--------------------

| Symbol | Meaning |

--------------------

|   B    | not A   |

|   D    | not C   |

|   H    | not G   |

|   K    | G or T  |

|   M    | A or C  |

|   R    | A or G  |

|   S    | C or G  |

|   V    | not T   |

|   Y    | C or T  |

|   W    | A or T  |

|   N    | unknown |- the nucleotide wittingly non-complementary and

|                  |  non-homology to any nucleotide of sequence

|   X    | A C G T |- the nucleotide wittingly complementary or 

|__________________|  homology to any nucleotide of sequence  

 

The user may create the list of from 1 to 50 oligonucleotides.

Active keys:

   Enter - fixes the typed in  working  window  sequence  as the being

tested oligonucleotide under current number (shown in  the left  upper

corner of window);

   F9 - stores the typed in  working  window  sequence at the  end  of

created list;

   F8 - removes the shown in  working  window  sequence from the list;

   F5 - allows to write the shown in working window  sequence  in file

     The use must define  the  path  and  name  of  file  (by  default

     "primlib.dat" in current directory) and press Enter.  Then he can

     type a short comment to stored oligonucleotide and press Enter or

     only  press  Enter  (then  the  primer  will  be  stored  without

     comments). If despite pressing Enter the user will press  Escape,

     the oligonucleotide will not be written  in  file.  If  the  file

     where the oligonucleotide is being stored already exist, the  new

     oligonucleotide will be added at the end of file );

   Up and Down arrows - allows moving along the list;

   Alt+R - allows to reorientate the 5' and 3' termini of oligonucleotide;

   Alt+C - allows to make the typed-in oligonucleotide complementary;

   Escape - closes the working  window  and  abolishes  all changes in

working window if they have not been fixed by Enter of F9.

 

     Sequence of being tested oligonucleotide(s) can be input  in  one

more way : being in the option "Sequences" You can find file  of  Your

interest and view it by F3-key.  After   pressing  F7  and  cursor's

occurring You can mark any number of symbols  (up to 60 - the  maximal

length of  tested  oligonucleotide).  Marking  and  unmarking  may  be

performed by Shift+Arrow-keys.  Only  marked  letters are taken to  be

the  tested  oligonucleotide.  Direction  of  marking  coincides  with

direction of oligonucleotide: the first  marked  symbol corresponds to

5'  terminus  and  the  last  marked  symbol  -  to  3'  terminus.  To

input  marked  string  as  the  oligonucleotide  -   press  F10   (the

oligonucleotide will be input under current number -  the  number  You

could see having opened option "Primer"). If you want  to  create  the

list - press F9 (the oligonucleotide will be  stored  at  the  end  of

list). If You want marked string to be input  in  complementary  way -

press Shift+F10 or Shift+F9 respectively. To cancel all You have marked

- press F7. To leave viewer -  press  Escape.  You  can  see  the text

of  input oligonucleotide(s) in option "Primer", where You can edit it.

If You did any changes in oligonucleotide's sequence - press Enter.

 

     Option "Sequences" allows to input sequences, on which  the  user

wishes to test oligonucleotide(s). This option completely  corresponds

to the same option in AUTO_SEARCH and all its operations are described

above.

     Alternatively, option "Directory"  allows to point path, name and

file's pattern of directory containing any number of sequence-files on

which testing of oligonucleotide is desirable.

 

     Option "Test on sequences" enables to test  oligonucleotide  with

respect to sequences pointed either in option "Sequences" or in option

"Directory". It opens three sub-options.

   1) Sub-option "Best energy"  allows  to  set  the  number  of  most

preferable in energetic terms sites of sequences for binding of tested

primer. To do it, enter the option (by Enter) press Enter  again  and,

after cursor's occurring, type the number. Search  of  set  number  of

sites may be performed on every sequence or on all  sequences  on  the

whole (switch "all" - "every" by Enter-key).

   2) Sub-option "Complementarity" allows to find sites  of  sequences

where tested  oligonucleotide  has level of complementarity  equal  or

exceeding the threshold set by user. The search may be performed in

three regimes:

  a) when "Total Complementarity" > 0 and "3'end Complementarity" = 0 -

search of sites of sequences having level of complementarity equal or

exceeding threshold set for "Total Complementarity";

  b) when "Total Complementarity" = 0 and "3'end Complementarity" > 0 -

search of sites of sequences having sufficient continuous complementa-

rity with 3' termini of tested oligonucleotide  independent  on  total

complementarity.

  c) if "Total Complementarity" > 0 and "3'end Complementarity" > 0 -

search of  sites  of  sequences  corresponding  to  both set levels in

combination.

The search may be carried out on both chains of sequences or  only  on

plus or minus chain (switch by Enter key).

   3) Sub-option "Homology search" is very similar to previous  option

but the  main  criterion  here  is  homology  of  oligonucleotide  and

sequence. Homology search may be performed in three regimes:

  a) when "Total Homology" > 0 and "Non-stop Homology" = 0 - search of

sites of sequences having level of homology equal or exceeding

threshold set for "Total homology";

  b) when "Total Homology" = 0 and "Non-stop Homology" > 0 - search of

sites  of  sequences  having  sufficient  continuous   homology   with

tested oligonucleotide independent on total homology.

  c) if "Total Homology" > 0 and "Non-stop Homology" > 0 -  search  of

sites of sequences corresponding to both set levels in combination.

  Items "Max.gap in primer" and "Max.gap in seq." allows to set the

maximal permissible size of gaps in primer/sequence (from 0 to 9) which

is taken into account during the homology search.

Like it is in previous sub-option, search of homology may be performed

on both chains of sequences or only on plus or minus chain.

 

     Option  "Self-test"  allows  to  obtain  information  about  some

properties of  tested  oligonucleotide  it-self.  Namely,  information

about melting temperature molecular weight and possibility of stem-loop 

structure formation is accessible. To obtain this information in output

file user must mark corresponding item inside "Self-test" (mark-unmark

by Enter-key). The length, annealing temperature and mol. weight of oli-

gonucleotide is also displayed in the active window of option "Primer".

Note, only actually probable hairpins will be displayed in  output-file.

 

     Option "Output file name" allows to define the name  and/or  path

for output file. By default the  name  "primtest.XXX"  with  extension

corresponding to the number of program's start is assigned.

Note, all possible or only one setting for test has  been  done  -  it

does not matter.

 

To start testing oligonucleotide(s) the user must open option  "Primer"

and fix in the working window the primer which user wants to test as the

first. Then the user must close the window and place the cursor on the

"Run". Sequential  pressing  Enter key will  be  followed  by  testing

oligonucleotide(s) from the list one after other.

========================================================================

 

 <<<<<<<<<<<<<<<

 << UTILITIES <<

 <<<<<<<<<<<<<<<

 

     This item of main menu involves three sub-programs:

"Output file treatment", "Complementary chain" and "New sequence type".

     "Output file treatment" allows to form, on the base  of  existing

output files new pairs of primers corresponding to newly set  tempera-

tures difference and/or permissible length of flanked  fragments.  The

user may also set the desirable number of pairs. The item  "Difference

of size" corresponds to similar option in "Universal" of "Auto_search"

and sets the maximal difference between the lengths  of  fragments  of

different sequences amplified by the same primer's pair. The files  in

format of "primers.XXX" or "pairs.XXX" may be subject for treatment.

     "Complementary chain" is designated for building "minus"-chain to

existing "plus"- chain of nucleotide sequence.  You have to point name

of file containing sequence you are interested in, and  name  of  file

for converted sequence.

 

     "New sequence type" is designated to facilitate typing-in new

nucleotide sequence parallelly and comparing it to related sequence-

pattern.

Option "Redesignate keys" allows to redesignate seven active keys denoting

nucleotides (g,a,t,c,n) and deletion ("-" symbol in newly typed sequence)

and insertion ("-" symbol in pattern sequence opposite the inserted

nucleotide in new sequence). Note, do not mix up insertion and deletion

symbols with standard Delete and Insert keys of keyboard. To redesignate

some key press Enter and after cursor occurence press any key you wish

to denote respective symbol.

Using the "Pattern sequence" option one can select the sequence-file which

will be used as reference pattern for typing new sequence.

    When the keys are comfortably redesignated and the pattern sequence is

selected one should Run the program. It takes and displays the pattern

sequence file so that the header part of file is presented without changes

but the sequence itself is presented as 60 nucleotide length lines (passive

lines) alternated with empty lines where new sequence may be typed (active

lines). The cursor can be placed only on active line. If the typed-in

symbol mismatches the respective nucleotide in passive line, the sound

signal will occur and this new nucleotide will be displayed as capital red

letter. In general, all mismatches are displayed as capital red letters.

Besides the redesignated keys the following ones are active:

Insert key -     turns on/off the insertion mode of editor (by default the

                 mode is "off");

Space-bar -      input space symbol;

Delete & BackSpace - have standard for all text editors functions;

Ctrl+BackSpace - removes the insertion symbol from the passive line (if any)

                 together with respective "inserted" symbol in active line.

                 If no "-" symbol is in passive line Ctrl+BackSpace works as

                 BackSpace.

F2 key -         allows to write both sequences (pattern and newly typed) in

                 file. This file will be recognized by program and typing new

                 sequence may be carried on again.

Shift+F2 -       allows to write only newly typed sequence in file in EMBL

                 gene bank format.

F7 key -         allows the search for short motifs. The user should type

                 the short (up to 60 nucl.) sequence for search and press

                 Enter. The 3' and 5' termini of typed-in sequence may be

                 reorientated by Alt+R keys or this sequence may be obtained

                 in complementary form by Alt+C keys. The 100 position with

                 most high homology will be stored in memory and the best

                 one will be displayed. To see all other positions user shall

                 press Ctrl+Right Arrow (moving in direction of less homology)

                 or Ctrl+Left Arrow. The homology level is determined taking

                 into account the possibility of 1-2 nucleotide

                 deletions/insertions. The search for short motifs may be

                 performed on sequences of no more than 50000 nucleotides

                 length (this value is valid if the header part of sequence-file

                 except the last line containing "SQ" or "ORI..." is removed).

F12 key -        allows to switch the direction of typing from the normal

                 left-to-right to the right-to-left direction and vise versa.

Ctrl+any key denoting the nucleotide - inputs the insertion symbol in passive

                 line and the "inserted" nucleotide in active line at the

                 same time.

Escape -         quit the program.

================================================================================

     THE FORMAT OF SEQUENCE FILES

 

     The only requirement to sequence file format is as follows:

The line preceding the first nucleotide line of file must begin from

the combination of capital letters "SQ" or "ORI" or "ORIGIN". If the file

you wish to handle as sequence file breaks this rule, please add necessary

letters in respective place.   

 

     OUTPUT FILES

 

     The file "primers.XXX"  contains  all  selected  primers  without

pair's formation. This file is preferable for "Output file treatment",

because some primers can not form pairs and therefore  are  absent  in

file "pairs.XXX".

In the left column of files "pairs.XXX", "primers.XXX", "location.XXX"

information about sense primers ( marked as (+)) is situated,  in  the

right column - information about anti-sense primers ( marked as (-)).

If program works in variant UNIVERSAL the files "primers" and  "pairs"

contain figures in brackets in  line  "Annealing  temperature".  These

figures mean  the  annealing  temperature  of  primer  connected  with

possible partial uncomplementarity of primer  in  target  place.  This

temperature shall be used during the first  4-5  cycles  of  PCR.  The

following cycles shall be performed at the temperature pointed without

brackets. If the figures in brackets and without any are the  same  it

means that the primer has complete complementarity in target places on

all sequences.

     Some primers obtained after work of SPECIFIC may be  supplied  by

special mark "*". They have high probability of  nonspecific  binding,

but are unable to be  extended  in  places  of  this  binding  due  to

uncomplementarity  of  their  3'-  termini  and  absence   of   3'-5'-

exonuclease activity of thermostable polymerases used  in  PCR.  These

primers will be selected only if there are no better ones.

     TERMINOLOGY

   MAX.ENERGY ( Gm) - the binding energy ( exactly the standard free

energy of Gibbs) of primer and template in specific place. If program

works in regime "Universal", the mean value of energies of binding of

primer with respective sites of all considered sequences is hadeled as

MAX.ENERGY (maximum)

   DELTA ( Gm - Gs) - difference between binding energies of primer and

template in specific and most profitable non-specific place (difference

between energetic maximum and submaximum).

 

 

     GENERAL INFORMATION AND PRINCIPLES

 

     There are some main features,  which  distinguish  the  presented

software from other programs for primer's choosing.

 

     1) First of all, it enables to treat several nucleotide sequences

and  to  select  primers,  which  are  universal  for  all  considered

sequences or, on the contrary,  specific  for  only  one  out  of  all

sequences. This capability of the program allows it to be useful,  for

example, for the development  of  PCR-based  diagnostic  systems.  The

algorithm exploited  in  program  allows  to  reveal  conservative and

variable sites of sequences without alignment's building.  The  method

is very reliable and quite rapid. It lifts principal limitations  from

the number of treated sequences and  allows finding  specific  primers

for one out of several very  similar sequences  or universal for very

unlike sequences.

 

     2) The program pays particular attention to the  evaluation  of

specificity of selected primers. Selected primer  must  be  able  of

reliable binding and extension in specific place of proper  sequence

(if working regime is "Specific") or  in  respective  sites  of  all

considered sequences (if regime is "Universal") and have  the  least

probability of primer-template binding and extension  in  any  other

place. To estimate the reliability of specific  and  probability  of

non-specific interactions the energetic criterion is proposed. It is

based on assumption that certain primer interacts with  template  in

random way, then the probability and reliability of  primer-template

binding is primarily defined by thermodynamic  stability  of  duplex

and most perfectly described by the standard free  energy  of  Gibbs

(dG).

So, the binding energy of  primer  and  template  is  estimated,  by

nearest-neighbor method according to  the  principle  "all-or-none".

The binding energy of primer estimated  in  its  specific  place  is

taken as an energetic maximum. If regime is  "Universal",  the  mean

binding energy of primer in its specific  sites  of  all  considered

sequences is taken  to  be  the  energetic  maximum.  Such  approach

enables to take into account both  the  destabilizing  influence  of

primer's partial uncomplementarity in  its  specific  site  and  the

probability of this uncomplementarity.

The energy is also  estimated  for  any  other  places  of  possible

extension of this primer  (places  where  3'termini  nucleotides  of

primer  are   complementary   to   sequence),   for   any   possible

conformations of it, including formation of  internal  loops,  bulge

loops, asymmetric loops and dangling ends.  The  permitted  size  of

bulge loop on the primer's side is up to 2 nucleotides, on the  side

of sequence - 1 nucleotide. The maximal value of binding  energy  in

any nonspecific place is taken as energetic submaximum. The  primers

having most high energetic maximum and the most  difference  between

maximum and submaximum are selected as the best ones. They form most

stable  bond  with  template  in  specific  site  and  have  minimal

probability of nonspecific interaction at  certain  conditions.  The

application of energetic criterions,  first  of  all  evaluation  of

submaximum, guarantees principally more high  accuracy  of  primer's

specificity estimation. Such accuracy may not be provided by usually

used for this goal criterion of complementarity.

     It must be noted that the data concerning  DNA-duplex  energies

and conditions of helix to coil transition  are  very  contradictory

and unsufficient. Moreover the conventional principle  "all-or-none"

describes such a  transition  not  perfectly  enough.  Nevertheless,

estimation of all primers in the same manner  makes  this  draw-back

rather negligible and enables to select the really best primers.

 

     3) The program allows to carry out the search and selection  of

primers within the interesting sites of sequences, or to  carry  out

selection of primers and formation of primer's pairs, which  provide

amplification of interesting fragment of sequences. It may  be  very

useful for the selections of primers for  site-directed  mutagenesis

or for preparation for cloning or sequencing.

 

     4) The program has a very important capability to adapt itself to

the treated sequences. A lot of  criterions  of  selection  and  other

values may be softened automatically, if no primer is selected  or  no

pairs are formed using the most stringent forms of  these  criterions.

You will obtain  " 0  pairs  are  formed "  and void output-files only

when virtually all possibilities are depleted. Of course, the  altera-

tion of criterions proceeds only within the reasonable limits.

 

     Besides to be high specific, selected primers have also some

properties:

 

a) they contain no sequence repeat structure;

b) they contain no large GC-rich sites and no stretched repeats of the

same nucleotides;

c) they are free of hairpins (the annealing temperature of primer must

be at least 25 C higher than melting temperature of most stable hairpin,

which could be formed by this primer);

d) they can not form any dimmer structures;

e) their annealing temperature is within limits set by user  ( but not

lower than 35 C and not higher than 73 C ).

The particular attention is paid to the 3'-ends of primers, since just

their  properties  determine  the  possibility  or  impossibility   of

primer's extension. For example, the universal primers  must  have  at

least three complementary nucleotides  at their  3'-terminies  in  all

target places on all sequences. On the other hand, during the search of

energetic submaximum ( place of most profitable nonspecific binding  ),

all sites, where primer has complementarity of even two 3'  nucleotides

are considered as  the  sites  of  possible  primer's  extension.  This

criterion may seem to be too stringent,  but  we  suppose  that  it  is

better to overdo in this term, than to overlook  potentially  dangerous

site.

 

     Requirements for pair's formation:

 

1) Difference between annealing temperatures of  both  primers  is  no

more than value set by user;

2) The size of fragments flanked by primers is within  limits  set  by

user;

3) Primers can not bind with each other (the maximal  possible  energy

of their binding must not exceed the submaximum of each primers);

4) 3'-end of one primer can not bind with any site of other one;

5) No one primer forms hairpin at the annealing temperature  of  second

primer in pair;

6) The length of fragments of different sequences amplified by univer-

sal primers do not differ from each other more then by  value  set  by

user.

 

     The presented software is developed on Turbo-C language and may be

used on every IBM-compatible computer.