MadSci Network: Biochemistry

Re: how blocking works in immunocytochemical analyis with serum or BSA .

Date: Sun Dec 24 09:21:17 2006
Posted By: Michel Ouellet, Projects leader
Area of science: Biochemistry
ID: 1165561964.Bc

Hi Sanal,

Proteins tend to stick to most things non-specifically (plastic, glass, other proteins, lipids, sugars, the surface of a cell, etc.). It it due to their natural charge and hydrophilicity/hydrophobicity. When you work with antibodies, you want to minimize non-specific binding in order to get the best signal to noise ratio you can achieve. In order to do this, a large amount of non-reactive protein such as bovine serum albumin, serum or others is added to the sample in order to coat non-specific protein binding sites with these non-reactive proteins. Serum, BSA, casein or gelatin can also be added to the immunostaining buffers (primary and secondary antibodies, if required) so that non-specific protein binding sites are always coated (association and dissociation is a highly dynamic process).

Now because of the large difference in concentration between BSA and the antibody as well as the inherent specificity of the antibody toward its antigen, only a small amount of antibody normally attaches to non-specific protein binding sites and most of it is instead associated with its antigen, therefore providing a good signal with minimal non-specific binding (i.e., background).

I hope this answered your question,


Current Queue | Current Queue for Biochemistry | Biochemistry archives

Try the links in the MadSci Library for more information on Biochemistry.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-2006. All rights reserved.