DENATURATION OF PROTEINS. V. N.M.R. STUDY OF THE ARGININE RESIDUES OF LYSOZYME

J. H. Bradbury, Raymond S. Norton

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Abstract

The heat denaturation of lysozyme has been studied by proton magnetic resonance spectroscopy at 220 MHz in water at pH 2.8. At 20°C a broad resonance is observed at 6.8δ due to the arginine NH2 resonances, which becomes a well defined triple resonance at 40°C, without any change in the rest of the spectrum. This sharpening of the arginine NH2 resonances is due to their increased mobilities and/or some normalisation of their chemical shifts. It is proposed that the surface structure of lysozyme is loosened at 40°C, without any change in the hydrophobic core and this is considered to be an intermediate phase in its heat denaturation. The heat denatured product at 80°C in D2O retains some noncovalent interactions, since further treatment with guanidine deuterochloride or mercaptoethanol causes sharpening of the aromatic region of the spectrum.

Original languageEnglish
Pages (from-to)295-302
Number of pages8
JournalInternational Journal of Peptide and Protein Research
Volume6
Issue number5
DOIs
Publication statusPublished - 1974
Externally publishedYes

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