期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1976
卷号：73
期号：6
页码：1979-1983
DOI：10.1073/pnas.73.6.1979
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Several of the carboxyl carbon atom resonances of hen egg-white lysozyme (mucopeptide N-acetylmuramoyl hydrolase, EC 3.2.1.17 ) have been resolved by 13C-nuclear magnetic resonance (NMR) at 68 MHz. The change in chemical shift of the carboxyl carbon atom resonances, as a function of pH, has enabled the distinction of these resonances against the background of many nontitrating carbonyl group resonances. Several apparent microscopic ionization constants have been determined from the carboxyl group NMR titration curves, and possible assignments are discussed. Preliminary experiments were carried out in the presence of cobaltous ion, and selective shifts of several resonances were observed. Our results indicate the possibility of the direct observation of a wide range of single functional groups of proteins in solution by NMR techniques.
