Doonan S, Fahmy H M
Eur J Biochem. 1975 Aug 15;56(2):421-6. doi: 10.1111/j.1432-1033.1975.tb02248.x.
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 beta 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.
已开发出一种在修饰半胱氨酸残基的N端侧对多肽进行特异性酶切的方法。赖氨酸残基通过三氟乙酰化被封闭，随后半胱氨酸残基转化为2-氨基乙基衍生物。用蜜环菌的赖氨酸特异性蛋白酶（Walton等人于1972年获得专利）消化修饰后的多肽，仅在2-氨基乙基半胱氨酸残基处发生切割。对于人血红蛋白的β链，其含有2个半胱氨酸和11个赖氨酸残基，在两个修饰的半胱氨酸处均观察到切割，但在赖氨酸处均未观察到切割。对于来自蜂毒的一种含有4个半胱氨酸和5个赖氨酸残基的多肽，仅在2个修饰的半胱氨酸处以及2个赖氨酸残基处发生切割。后一种情况下的切割模式可以根据该多肽的氨基酸序列来解释。
