Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A metallothionein isoform metallothionein-II was isolated from the livers of zinc acetate-treated rats. Metallothionein-II, which showed a single band on polyacrylamide gel electrophoresis, was subjected to two kinds of anti-ulcer screening systems. It was shown that intravenously administered metallothionein-II suppressed the formation of rat water-immersion stress- and HCl-ethanol-induced gastric ulcer significantly. The effect may partly be derived from the zinc contained in the metallothionein-II. However, the effect of metallothionein-II was much stronger than that of an equivalent mole of zinc. Apparently, metallothionein-II had an anti-ulcerogenic activity not based on the effect of intrinsic zinc.
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PMID:Suppression of gastric ulcer induced by stress and HCL-ethanol by intravenously administered metallothionein-II. 334 6

Two isoproteins of calf liver metallothionein (MT) have been isolated, purified, and characterized by atomic absorption, ultraviolet absorption, electron spin resonance, and 113Cd nuclear magnetic resonance spectroscopy. Native calf liver MT was found to contain both Cu+ and Zn2+ in a mole ratio of approximately 0.75. Selective replacement of the native Zn2+ with 113Cd2+ can be accomplished in vitro by adding 113CdCl2 to the homogenate before chromatography. Both isoproteins of metallothionein thus prepared contain approximately 3.9 g atoms of Cd2+ and 2.6 g atoms of Cu+/mol of protein. No ESR signal was found, indicating that either Cu+ or antiferromagnetically coupled Cu2+ is the form of copper present. Arguments in support of the former state are presented. Unlike the native 113Cd,Zn MT from rabbit liver, calf liver 113Cd,Cu MT exhibits a remarkably simple 113Cd NMR spectrum. Four major resonances were found for each isoprotein, in the same positions as the resonances assigned to the metals in the four-metal cluster A of rabbit liver metallothionein. This conclusion was confirmed by homonuclear decoupling experiments. This result in conjunction with the stoichiometry of bound metal ions found in the native protein suggests that Cu+ is bound selectively to the three-metal cluster B sites, and that one homogeneous protein fraction predominates. Three minor resonances to higher field are observed in the 113Cd NMR spectrum of calf liver MT-1 and one in calf liver MT-2, which may be attributed to a small fraction of cluster B with one Cu+ replaced by 113Cd2+. The possible biological significance of the different metal ion specificities of cluster A versus cluster B is discussed.
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PMID:Evidence for site-selective metal binding in calf liver metallothionein. 705 17

113Cd NMR has been used to determine the structures of the multiple metal-binding sites in the two major isoproteins of metallothionein from mammalian livers (rabbits, calf, and human) and from Scylla serrata hepatopancreas. The native protein isolated from the livers of rabbits that had been subjected to repeated injections of 113CdCl2 contains an appreciable amount of Zn2+ in addition to 113Cd2+, ranging from 2 to 3 g-atoms of a total metal content of 7 g-atoms/mol of protein. The native Zn2+ can be replaced in vitro with 113Cd2+ to give a 113Cd NMR spectrum consisting of eight distinct multiplets in the chemical shift range of 604-670 ppm. The multiplet structure is due to 113Cd-113Cd scalar coupling arising from two-bond interactions between 113Cd2+ ions linked to one another by bridging cysteine thiolate ligands. Analysis of the 113Cd spectra by selective homonuclear 113Cd decoupling techniques showed that both isoproteins of rabbit liver metallothionein contain two separate metal clusters, one containing Cd2+ ions (cluster A) and the other containing three (cluster B). Structures for the clusters are proposed that account for the 113Cd chemical shift and spin coupling data and the participation of all 20 cysteine residues in metal ligation. The 113Cd NMR spectrum of 113Cd2+-reconstituted human liver metallothionein is remarkably similar to that of the rabbit and the analysis confirms that it contains the same two-cluster arrangement. Native calf liver metallothionein was found to contain copper and Zn2+ and the in vitro exchange with 113Cd2+ selectively replaces only the Zn2+. The reconstituted protein contains 3.9 g-atoms of 113Cd2+ and 2.6 g-atoms of copper and the 113Cd NMR spectrum showed four major multiplets with identical chemical shifts to the resonances previously assigned to the four-metal cluster A. This result was confirmed by homonuclear decoupling experiments. The 2.6 g-atoms of electron spin resonance-silent copper in this sample is presumably selectively bound to the three-metal cluster B sites. Both isoproteins of metallothionein isolated from 113Cd2+-injected mud crabs (S. serrata) contain only 113Cd2+. The analysis of the 113Cd NMR spectra show that the total of six metals bound per mole of crab metallothionein-1 (MT-1) and MT-2 are arranged in two separate three-metal clusters.
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PMID:Structure elucidation of the metal-binding sites in metallothionein by 113Cd NMR. 714 Sep 98