| Literature DB >> 4501576 |
D J Patel, C K Woodward, F A Bovey.
Abstract
A resonance (designated a) due to an exchangeable proton titrates (pK(a) = 6.1) between 11.5 and 13 ppm in the nuclear magnetic resonance spectrum of RNase A-0.2 M NaCl in H(2)O at 20 degrees . Comparison with models has permitted assignment to a ring-nitrogen proton of histidine in slow exchange with solvent H(2)O. The pH and temperature-dependent line-width changes of resonance a are analyzed in terms of an exchange between histidine and protonated histidine, without the necessity to invoke any exchange processes associated with protein conformational changes. Several other resonances due to exchangeable protons are observed between 10 and 15 ppm in the nuclear magnetic resonance spectrum of RNase A in H(2)O.Entities:
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Year: 1972 PMID： 4501576 PMCID： PMC426515 DOI： 10.1073/pnas.69.3.599
Source DB: PubMed Journal: Proc Natl Acad Sci U S A ISSN： 0027-8424 Impact factor: 11.205