Nanosecond flash photolysis study of carbon monoxide binding to the beta chain of hemoglobin Zürich [beta 63(E7)His leads to Arg].

D. D. Dlott, H. Frauenfelder, P. Langer, H. Roder, E. E. DiIorio

Research output: Contribution to journalArticle

Abstract

Binding of carbon monoxide to beta chains of hemoglobin Zürich has been studied by flash photolysis over the time range of nanoseconds to seconds at temperatures from 20 to 300 K. From 20 to 200 K a single rebinding process (process I) is seen, characterized by a distribution of barrier heights with a peak enthalpy of 2.3 kJ/mol. Above 200 K some ligands escape from the pocket into the matrix, and above 260 K recombination from the solvent sets in. Process I is visible up to 300 K, but above 200 K its rate remains essentially constant at about 4 X 10(8)s -1. Above about 250 K, process I is exponential in time, indicating rapid conformational relaxation. The results are discussed within the framework of a sequential model for ligand binding.

Original languageEnglish (US)
Pages (from-to)6239-6243
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume80
Issue number20
DOIs
StatePublished - Oct 1983

ASJC Scopus subject areas

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