CHEMICAL AND BIOLOGICAL CHARACTERIZATION OF METHYLATED BOVINE GROWTH HORMONE

被引:5
作者
LIBERTI, JP
ALFANO, J
SONENBER.M
机构
[1] Division of Endocrinology, Sloan-Kettering Institute, New York
关键词
D O I
10.1016/0005-2795(69)90239-6
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Bovine growth hormone has been methylated in acid methanol under various conditions. The methylated hormone has been characterized biologically and chemically. Bovine growth hormone derivatives with 6 methyl groups per mole of 22 000 mol. wt. (15% esterification) or less retained full growth-promoting activity. There was a progressive loss of biological activity as the number of methyl groups introduced increased from 8 to 15 per mole. A complete loss of biological activity occurred when 50% or more of the free carboxyl groups were esterified. Methylation was complete after 36 h of reaction. Native bovine growth hormone contains 40.3 ± 0.7 free carboxyl groups per mole determined by potentiometric titration. Ester analysis of the methylated hormone reacted for 36 to 72 h revealed 41.4 and 40.8 methyl esters per mole respectively. Amino acid analysis of native and completely methylated bovine growth hormone revealed 41.6 residues as aspartic and glutamic acid. Evidence obtained from starch-gel electrophoresis in conjunction with biological assays supports the conclusion that the decrease in growth-promoting activity of the growth hormone derivatives is related to the degree of esterification and not the reaction conditions employed. © 1969.
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页码:176 / &
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