Hemerythrin. Structural details from spectroscopic analyses

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:7170855

Shiemke, A K

The binuclear active site of hemerythrin consists of octahedral iron atoms bridged by an oxo group (O/sup 2 -/). The vibrations of this Fe-O-Fe unit dominate the resonance Raman spectra of most forms of hemerythrin. From the analysis of such spectra, details of the binding site structure of oxy, hydroxomet and methemerythrin have been revealed. The bound O/sub 2/ group of oxyhemerythrin is identified as a hydroperoxide based on shifts of the O-O and Fe-O/sub 2/ stetching vibrations in D/sub 2/O and /sup 18/O/sub 2/. The discovery of the Fe-O-Fe vibrations of oxyhemerythrin permit the conclusion that the hydroperoxide is bound end-on to a single iron of the binuclear cluster. The low frequency of the oxyhemerythrin nu/sub x/ (Fe-O-Fe) vibration (486 cm/sup -1/) relative to those of the methemerythrins (506-516 cm/sup -1/) is attributed to this hydrogen bond interaction. In the resonance Raman spectrum of hydroxomethemerythrin two peaks at 492 and 506 cm/sup -1/ shift to 478 and 491 cm/sup -1/, respectively, upon /sup 18/O substitution of the bridge, identifying both as nu/sub s/(Fe-O-Fe) vibrations, and indicating the existence of two distinct conformations of the metal center. The low frequency of the 492 cm/sup -1/ Fe-O-Fe vibration is attributed to an intramolecular hydrogen bond between the oxo bridge and the hydroxide ligand in the cis conformation. The 506 cm/sup -1/ nu/sub s/(Fe-O-Fe) mode is attributed to the trans conformation which lacks this hydrogen bond. A temperature-dependent effect on the Raman spectrum of unligated methemerythrin is also observed. Below 200 K, a second nu/sub s/(Fe-O-Fe) mode at 490 cm/sup -1/, is observed in addition to the 510 cm/sup -1/ mode, indicating that the metal center may adopt two conformations.

• Research Organization: Oregon Graduate Center, Portland (USA)
• OSTI ID: 7170855
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CARBOXYLIC ACIDS
CONFORMATIONAL CHANGES
ERYTHROCYTES
EVEN-EVEN NUCLEI
HEAVY WATER
HEME
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
ISOTOPES
LASER SPECTROSCOPY
LIGHT NUCLEI
MATERIALS
MOLECULAR STRUCTURE
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PIGMENTS
PORPHYRINS
PROTEINS
RAMAN SPECTRA
RAMAN SPECTROSCOPY
SPECTRA
SPECTROSCOPY
STABLE ISOTOPES
TEMPERATURE DEPENDENCE
WATER