Primary structure and spectroscopic studies of Neurospora copper metallothionein
When Neurospora crassa is grown in the presence of Cu(II) ions, it accumulates the metal with the concomitant synthesis of a low molecular weight copper-binding protein. The molecule binds 6 g-atom of copper per mole protein (M/sub r/ = 2200) and shows a striking sequence homology to the zinc- and cadmium-binding vertebrate metallothioneins. Absorption, circular dichroism, and electron paramagnetic resonance spectroscopy of Neurospora metallothionein indicate the copper to be bound to cysteinyl residues as a Cu(I)-thiolate complex of the polymeric ..mu..-thiolate structure (Cu(I)/sub 6/RS/sub 7/)/sup -/. The spectroscopic properties of the fully substituted forms are indicative of a distorted tetrahedral coordination. However, metal titration of the apoprotein shows the third metal ion to be differently coordinated than the other two metal ions. This difference can be explained by the presence of only seven cysteine residues in Neurospora metallothionein as opposed to nine cysteine residues in the three-metal cluster of the mammalian metallothioneins.
- Research Organization:
- Univ. of Padova, Italy
- OSTI ID:
- 5386408
- Journal Information:
- Environ. Health Perspect.; (United States), Journal Name: Environ. Health Perspect.; (United States) Vol. 65; ISSN EVHPA
- Country of Publication:
- United States
- Language:
- English
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560302 -- Chemicals Metabolism & Toxicology-- Microorganisms-- (-1987)
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIOSYNTHESIS
COPPER
ELEMENTS
FUNGI
METALLOPROTEINS
METALLOTHIONEIN
METALS
NEUROSPORA
ORGANIC COMPOUNDS
PLANTS
PROTEINS
SPECTROSCOPY
STOICHIOMETRY
SYNTHESIS
TRANSITION ELEMENTS