Biotinylation of N-terminus only

[Keith Robison]

tshin at husc8.harvard.edu (Tae Shin) writes:

>I am interested in labelling a protein (not an antibody) using N-hydroxy-
>succinimide biotin.  The standard protocol requires this labelling be done at
>pH9, which should label all of the accesible lysine sidechains and the 
>N-terminus.  I have heard that by lowering the pH (to about 6) one should be
>able to label the N-terminus selectively.  Has anyone had any experience with
>this?  Any comments would be welcome.  Thanks.

>T.B.Shin
>tshin at husc8.harvard.edu

I don't know if anyone has done this with biotin, but you should
check out the following reference by our own Dan Jay:


Jay, DG.  1984.  JBC 259:15572-15578.
	A general procedure for the end labeling of proteins and positioning
	of amino acids in the sequence.

In brief, the scheme is to perform a single round of Edman degredation
on the protein.  This results in a protein which is missing the N-terminal
amino acid, but with all its lysines blocked with the Edman group.  You
can then proceed to label the remaining N-terminus specifically.



Keith Robison
Harvard University
Department of Cellular and Developmental Biology
Department of Genetics / HHMI

robison at ribo.harvard.edu