hi u refer principles and techniques of biochemistry and molecular biology by keith wilson and john walker...

Thank you, I did but there is reference only for polymerization of acryl/bisacryl by APS but not anything about SDS and its effect on denaturation

1. When a protein mixture is heated to 100 °C in presence of SDS, the detergent wraps around the polypeptide backbone. It binds to polypeptides in a constant weight ratio of 1.4 g/g of polypeptide. In this process, the intrinsic charges of polypeptides becomes negligible when compared to the negative charges contributed by SDS. Thus polypeptides after treatment becomes a rod like structure possessing a uniform charge density, that is same net negative charge per unit length. Mobilities of these proteins will be a linear function of the logarithms of their molecular weights.

Without SDS, different proteins with similar molecular weights would migrate differently due to differences in mass charge ratio, as each protein has an isoelectric point and molecular weight particular to its primary structure. This is known as Native PAGE. Adding SDS solves this problem, as it binds to and unfolds the protein, giving a near uniform negative charge along the length of the polypeptide.(http://en.wikipedia.org/wiki/SDS-PAGE)

2.SDS (sodium dodecyl sulfate) is a detergent (soap) that can dissolve hydrophobic molecules but also has a negative charge (sulfATE) attached to it. Therefore, if a cell is incubated with SDS, the membranes will be dissolved and the proteins will be soluablized by the detergent, plus all the proteins will be covered with many negative charges. The end result has two important features: 1) all proteins contain only primary structure and 2) all proteins have a large negative charge which means they will all migrate towards the positve pole when placed in an electric field.(http://www.davidson.edu/academic/biology/courses/molbio/sdspage/sdspage.html)

Hello Yasar,

Thanks for the info, good explanation.

Regards,

Dr Preetha Anil

Hi Yasar,

Thank you for the explanation, Really good Indeed

Still, There are some more to sort out.... One SDS molecule will bind to 2 Amino acids in the polypeptide chain. The query is where does this bonding takes place.

http://olw.mit.edu/media/glossary/sodium_dodecyl_sulfate.jpg

Say for an example, for a polypetide chain with -----------( Arg Gly Asp Glu Lys)---------

how the binding will occurand where the bonding will occur,

Since Arg is is possitive, Gly is neutral, Asp is negative and glu is negative and lys is positive... In this case, actually what happens is tha " the resultant protein is uniformly negative, but what happens to the charge of individual amino acids and how does the bonding occurs????????? Interesting na .............

We need to find the answer, Hope we could.... Requesting more brains to think of it

Shyam