European Journal of Biomedical and Pharmaceutical Sciences

METTALOENZYMES AND THEIR MECHANISM IN HUMAN BODY

D. K. Awasthi* and Divya Pandey

ABSTRACT

Transition metal chemistry is an integral part of coordination chemistry and its ever growing importance and applications encompass many fields. Especially since transition metals form an important part of bioinorganic chemistry, being essential to life, and also with the spawning of newer uses in organic synthesis. In our present study, we stress upon the following metals nickel, zinc, cadmium, cobalt, copper, manganese and vanadium. Nickel occurs in the oxidation states -1 to +4 with +2 being most common and relevant biologically. The overwhelming majority of Ni(II) complexes have coordination numbers four, five and six with three, seven and eight being rare. The geometries exhibited by nickel are square planar, tetrahedral, octahedral, trigonal bipyramidal and square pyramidal. Nickel plays a fundamental role in DNA and RNA metabolism. Zinc exhibits a rich variety of stereochemistry with geometries ranging from tetrahedral, square pyramidal, trigonal bipyramidal and octahedral. Zn(II) ion bound to imidazole ligands of aminoacid residue histidine form the biologically active zinc metalloprotein. Zn+2 complexes of ATP accelerate hydrolysis of polyphosphates and are of relevance to RNA and DNA polymerases. Zinc metalloenzymes participate directly in the catalytic process and serve stabilize the protein structure.

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