Relationship between Heme Binding Site Structure and Heme Orientations of Two Ferrocytochrome b5s. A Study in Prosthetic Group Recognition

Thomas C. Pochapsky, Stephen G. Sligar, Gerd N. La Mar, Stuart J. McLachlan

Research output: Contribution to journalArticlepeer-review

Abstract

The heme binding sites of two b5 cytochromes, one isolated from beef liver and the other sequentially identical with the globular portion of rat liver cytochrome b5 and expressed bacterially from a synthetic gene, have been characterized in the diamagnetic reduced state by one-and two-dimensional NMR techniques. Both proteins are heterogeneous in structure in the vicinity of the heme prosthetic group, the result of two possible heme binding orientations. Equilibrium ratios of the two orientations differ between the oxidized beef and bacterially expressed rat proteins, with a ratio of 9:1 of the two isomers in the beef and a 6:4 ratio in the rat. A kinetic (1:1) mixture of the two forms may be trapped by reduction of protein freshly prepared by reconstitution of the apoprotein with hemin. Structural differences between the beef and bacterially expressed rat protein in the vicinity of the heme pocket were determined by nuclear Overhauser effect experiments. Structural differences between the two proteins are discussed in relation to differences in heme orientational equilibria.

Original languageEnglish (US)
Pages (from-to)5258-5263
Number of pages6
JournalJournal of the American Chemical Society
Volume112
Issue number13
DOIs
StatePublished - Jan 1990

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Fingerprint

Dive into the research topics of 'Relationship between Heme Binding Site Structure and Heme Orientations of Two Ferrocytochrome b5s. A Study in Prosthetic Group Recognition'. Together they form a unique fingerprint.

Cite this