Strigency calculation


Calculation of Washing and Hybridization Stringencies

The Excel Spreadsheet at this link will allow calculation of washing stringencies from SSC concentration (e.g. 2x or 0.1x), formamide percentage (e.g. 40%) and temperature.

If not, the filename stringen.xls at the end of the web address may work.

Here is a typical example

Stringency calculation
%GC 55
probe length 20  (after labelling)
formamide 40  percentage
SSC x 2  in x of the 1 x SSC (20x SSC is 0.33 M Na)
Hyb temp 37
0.41gc 22.55
[Na+] 0.66
16.6LogNa -2.99557
500/l 25
.61form 24.4
1 mismatch factor (1 for >150bp. 5 for <20bp)
Tm 51.65443
String 85.34557

Pat Heslop-Harrison/Trude Schwarzacher December 2003