Related Experiment Video
Updated: Aug 29, 2026

Methods to Identify the NMR Resonances of the 13C-Dimethyl N-terminal Amine on Reductively Methylated Proteins
Published on: December 12, 2013
Nuclear-magnetic-resonance-spectroscopic studies of the amino groups of insulin
Abstract:
The amino groups of insulin have been studied by 1H and 13C 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 epsilon-CH2 and delta-CH2 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 pKapp 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 Nepsilon-(CH3)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.
More Related Videos
12:47Nuclear Magnetic Resonance Spectroscopy for the Identification of Multiple Phosphorylations of Intrinsically Disordered Proteins
Published on: December 27, 2016
14:55Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Related Concept Videos
Nuclear Magnetic Resonance (NMR): Overview
NMR spectroscopy generates a spectrum where the characteristic absorption frequencies of the sample are...
Mass Spectrometry of Amines
Applications Of NMR In Biology
The...
NMR Spectroscopy Of Amines
Other Nuclides: 31P, 19F, 15N NMR
While fluorine-19 and phosphorous-31 have high natural abundances (100%) and positive gyromagnetic ratios, nitrogen-15 has a low natural abundance and a negative gyromagnetic ratio. However, nitrogen-15 is still preferred over nitrogen-14 (which has a high...
Insensitive Nuclei Enhanced by Polarization Transfer (INEPT)