Open AccessSpecific Enzymic Cleavage of Polypeptides at Cysteine Residues
Author(s) -
DOONAN Shawn,
FAHMY Hisham M. A.
Publication year - 1975
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1975.tb02248.x
Subject(s) - cysteine , cleavage (geology) , chemistry , biochemistry , stereochemistry , biology , enzyme , paleontology , fracture (geology)
A method has been developed for specific enzymic cleavage of polypeptides at the N‐terminal side of modified cysteine residues. Lysine residues are blocked by trifluoroacetylation and cysteine residues subsequently converted to the 2‐aminoethyl derivatives. Digestion of the modified polypeptide with the lysine‐specific protease from Armillaria mellea (patented by Walton et al., (1972) occurs only at 2‐aminoethylcysteine residues. With the β chain of human haemoglobin, which contains 2 cysteine and 11 lysine residues, cleavage was observed at both modified cysteines but at none of the lysines. In the case of a polypeptide from bee venom which contains 4 half‐cystine and 5 lysine residues, cleavage occurred at only 2 of the modified cysteines and also at 2 lysine residues. The pattern of cleavage in the latter case can be interpreted in terms of the amino acid sequence of the polypeptide.