Gupta MN, Vithayathil PJ. Chemical modification of methionines of ribonuclease A with o-benzoquinone.
INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1980;
15:236-42. [PMID:
7380607 DOI:
10.1111/j.1399-3011.1980.tb02572.x]
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Abstract
The accessibility of methionines in RNAase A to reaction with OBQ has been studied at highly acidic pH. The differences between the rate constants of reactions of the methionine and methionines of RNAase A with OBQ is a reflection on the limited accessibility of methionines in the protein conformation. Nevertheless, at sufficiently high OBQ concentration, all the four methionines of the enzyme can be modified. At lower concentration of OBQ, a derivative may be prepared in which a specific methionine is modified. The introduced chromophore ionizes at around pH 3 in this derivative. The derivative has partial activity towards RNA which is enhanced on addition of S-protein.
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