Metallothionein structure

Garvey JS. Metallothionein structure/antigenicity and detection/quantification in normal physiological fluids. Environ Health... 

Kagi JHR, Kojima Y, Berger C, Kissling MM, Lerch K, Vasak M (1979) Metallothionein structure and evolution. In Weser U (ed) Metalloproteins. Georg Thieme, Stuttgart New York, p 194... 

B. Metal Binding and Dynamic Aspects of Metallothionein Structure... 

Otvos ID, Liu X, Li H, Shen G, Basti M (1993) Dynamic aspects of metallothionein structure. In Suzuki KT, Imura N, Kimura K (eds) Metallothionein III. Birkhauser, Basel, pp 57-74... 

Investigation of the structure of metallothionein has been done many times and published in various types of journals [3-5, 116-121]. There are 88 review entries in ISI Web of Knowledge related to the key word metallothionein structure . These materials cover the time line from the half of eighties to the present. Most works focus on the description of the structure of metallothionein in connection with metal ions, especially on the binding metal ions into the structure of MT. Binding metal ions into the structure of MT is closely connected with its biological functions [92]. 

R31. Elucidation of metallothionein structure by cadmium-113 NMR Otvos, J. D. Armitage, I. M. in Biochemical Structure Determination by NMR Bothner-By, A. A. Glickson, J. D. Sykes, B. D. Eds. Dekker New York, 1982 pp. 65-96, 43 references. Covers structural characterization of metal-binding sites of metallothioneins from crab hepatopancreas and rabbit liver. 

The situation is different for other examples—for example, the peptide hormone glucagon and a small peptide, metallothionein, which binds seven cadmium or zinc atoms. Here large discrepancies were found between the structures determined by x-ray diffraction and NMR methods. The differences in the case of glucagon can be attributed to genuine conformational variability under different experimental conditions, whereas the disagreement in the metallothionein case was later shown to be due to an incorrectly determined x-ray structure. A re-examination of the x-ray data of metallothionein gave a structure very similar to that determined by NMR. 

Olafson RW, WD McCubbin, CM Kay (1988) Primary- and secondary-structural analysis of a unique prokaryotic metallothionein from a Synechococcus sp. cyanobacterium. Biochem J 251 691-699. 

Robbins, A.H. and Stout, C.D. (1992) Metallothioneins Synthesis, Structure and Properhes of Metallothioneins, Phytochelatins, and Metal-Thiolate Complexes (eds M.l. ShDman, C.F. Shawlll and KT. Suzuki), VCH Publishers, Weinheim, pp. 31—54. 

Otvos, J.D., Petering, D.H. and Shaw, C.F. Ill (1989) Structure - Reachvity Relationships of Metallothionein, a Unique Metal-Binding Protein. Comments on Inorganic Chemistry, 9,1-35. 

Mammalian metallothioneins typically bind seven metal ions in cluster structures, with bridging sulfur groups, as seen in the x-ray structure of the Cd5Zn2MT complex (86). It is therefore difficult to develop a simple formation-constant description for the binding of metal ions to MT (87), considering that protonation-deprotonation equilibria of the free protein itself should also be taken into account. However, the usefulness of Table VIII as a guide to the affinity of metal ions for mercapto donor ligands is seen in that the ability of metal ions to... 

Both copper and zinc appear to be stored in many bacteria in cysteine-rich proteins, called metallothioneins, which will be discussed from a structural point of view later in the chapter. The expression of these metal sequestering, low-molecular weight, cysteine-rich proteins, is often induced by both monovalent Cu(I) and divalent Zn(II), as well as by the non-biologically necessary, but potentially toxic, Ag(I) and Cd(II). 

It turns out that the six-membered Cu3( -8)3 rings are paradigmatic units. This type of ring system has been incorporated into current models of metallothioneins [low-molecular-weight proteins which are believed to play a key role in metal metabolism (cf. references in 136)]. The structural chemistry of the Ag complexes seems to be different. Monocyclic Ag(8 ) rings can be linked via bridging ligands as in [(86)Ag(88)Ag(86)] (133) or condensed as in [Ag2(86)2] " (28) (126). 

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