Skip to main content
OSTI.GOVU.S. Department of Energy Office of Scientific and Technical Information
U.S. Department of Energy
Office of Scientific and Technical Information
 

Spectroscopic and magnetic properties of the complexes of the heme octapeptide from cytochrome c

Technical Report ·
OSTI ID:5526025
Detailed ligand binding effects have been examined in a model system of cytochrome c, the N-acetylated ferric heme octapeptide (N-H8PT) directly isolated from horse heart cytochrome c. The room temperature absorption and magnetic circular dichroism (MCD) spectra of the complexes of N-H8PT with various external ligands such as F/sup -/, H/sub 2/O, OH/sup -/, N/sub 3//sup -/, imidazole (Im) and CN/sup -/ are found to behave generally as predicted from ligand field considerations. There is a direct correlation between the Soret absorption band position, ..beta.. band intensity or the Soret MCD intensity and susceptibility. The N-acetylated methionine complex of the N-H8PT, however, exhibits thermal equilibrium of spins between high and low spin states, while cytochrome c exists in the purely low spin state. Temperatre dependence of paramagnetic susceptibility of the methionine complex yields ..delta..H/sup 0/ = -7.6 kcal/mole and ..delta..S/sup 0/ = -25.9 e.u. for a high spin to low spin transition demonstrating a compensation effect between the two thermodynamic parameters. The low temperature ESR spectrum of the methionine complex indicates a low spin ground state with g values at 2.91, 2.31, and 1.51 which are distinct from the g values of cytochrome c. The axial (..delta..) and rhombic (V) distortion parameters in the t/sub 2g/ set of orbitals correspond to 1200 cm/sup -1/ and 780 cm/sup -1/, respectively. From these results, a model is proposed to account for the uniqueness of the methionine complex: a change in Fe-S distance may play a role in regulating the redox properties of cytochrome c.
Research Organization:
California Univ., Berkeley (USA). Lawrence Berkeley Lab.
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
5526025
Report Number(s):
LBL-10122
Country of Publication:
United States
Language:
English

Similar Records

CORRELATION BETWEEN THE OPTICAL AND MAGNETIC PROPERTIES OF FERRIC N-ACETYLATED HEME OCTAPEPTIDE COMPLEXES
Journal Article · Thu May 01 00:00:00 EDT 1980 · Interaction between Iron and Proteins in Oxygen and Electron Transport · OSTI ID:1070084
Electronic state of heme in cytochrome oxidase. II. Oxidation-reduction potential interactions and heme iron spin state behavior observed in reductive titrations
Journal Article · Sun Apr 09 23:00:00 EST 1978 · J. Biol. Chem.; (United States) · OSTI ID:7091648
Effects of the Tyr-67 acetylation on the heme crevice structure of horse heart cytochrome c derivatives
Conference · Thu May 01 00:00:00 EDT 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) · OSTI ID:5179890

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ABSORPTION SPECTRA
AMINO ACIDS
ANIMALS
BIOCHEMICAL REACTION KINETICS
BODY
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
CHEMICAL BONDS
CYTOCHROMES
DICHROISM
ELECTRON SPIN RESONANCE
ELEMENTS
GLOBIN
HEART
HEME
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HORSES
IRON
KINETICS
LIGANDS
LIPOTROPIC FACTORS
MAGNETIC PROPERTIES
MAGNETIC RESONANCE
MAMMALS
METALS
METHIONINE
MYOGLOBIN
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANS
PEPTIDES
PHYSICAL PROPERTIES
PIGMENTS
POLYPEPTIDES
PORPHYRINS
PROTEINS
REACTION KINETICS
RESONANCE
SPECTRA
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
THERMODYNAMICS
TRANSITION ELEMENTS
VERTEBRATES