Open AccessNuclear‐Magnetic‐Resonance‐Spectroscopic Studies of the Amino Groups of Insulin
Author(s) -
BRADBURY J. Howard,
BROWN Larry R.
Publication year - 1977
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1977.tb11627.x
Subject(s) - insulin , lysine , random hexamer , phenylalanine , nuclear magnetic resonance spectroscopy , resonance (particle physics) , chemistry , spectroscopy , glycine , zinc , crystallography , amino acid , biochemistry , stereochemistry , biology , physics , endocrinology , organic chemistry , atomic physics , quantum mechanics
The amino groups of insulin have been studied by 1 H and 13 C nuclear magnetic resonance spectroscopy in insulin, zinc‐free insulin and methylated insulin. By difference spectroscopy it is possible to follow the shift with pH of the ɛ‐CH 2 and δ‐CH 2 proton resonances of lysine‐B29 in insulin. In methylated insulin the dimethyl proton resonances of glycine‐A1, phenylalanine‐B1 and lysine‐B29 can be followed as a function of pH. In native insulin p K app values of 6.7 and 8.0 are obtained for phenylalanine‐B1 and glycine‐A1 (the assignment is tentative) and 11.2 for lysine‐B29. Separate resonances have been observed from the lysine‐B29 N ɛ ‐(CH 3 ) 2 group for the monomeric and dimeric forms of methylated insulin, which indicates a small change in the environment of lysine‐B29 on dimerisation. The nuclear magnetic resonance spectral characteristics of these groups are, in general, consistent with the overall structure of the crystal form of the 2‐zinc insulin hexamer.