Abstract
Proton magnetic resonance (PMR) spectra of 21 commonly occurring amino acids dissolved in CF 3COOH or CF 3COOD were recorded and analyzed in terms of proton chemical shifts, relative to (CH 3) 4 Si (TMS) as internal standard, and proton spin-spin coupling constants. The results were used for an analysis of PMR spectra of insulin and the individual A and B chains (as S-sulfonates), all dissolved in CF 3COOH or CF 3COOD. In the unusually high magnetic field applied (ca. 50,000 oersteds) large chemical shifts are found. Resonances from specific protons in arginine, alanine, asparagine, glycine, histidine, lysine, phenylalanine, threonine, and tyrosine residues are observed separately in single recordings. The γ-CH 2 protons of glutamic acid and glutamine residues form one separate band at 2.70 ppm, the CH 3 protons of leucine, isoleucine, and valine form another separate band at 1.00 ppm. Only proton resonances from cysteine, proline, and serine residues give no easily accessible evidence of their presence but they contribute significantly to the intensity versus chemical shift integrals.
Published Version
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