BIOCHEMICAL STUDIES IN RELATION TO GLUTAMATE DEHYDROGENASE IN Piper Nigrum (L.)

Abstract

Black pepper, the king of spices, the most important and widely used spice in the world is the dried mature berries of P. nigrum L. Inorganic nitrogen is assimilated into amino acids glutamine, glutamate, asparagines and aspartate which serve as important nitrogen carriers in plants. The enzymes glutamine synthetase (GS) EC. 6.3.1.2, glutamate synthase (GOGAT) E.C. 1.4.1.14, glutamate dehydrogenase (GDH) E.C.1.4.1.4, aspartate aminotransferase and asparagine synthetase are responsible for biosynthesis of these amino acids. Although extensive studies have been carried out on the epidemiology of the diseases and agronomical aspects of P. nigrum, very few studies have been made on the enzymological aspects especially that associated with the nitrogen assimilation. A better understanding of the various properties of the enzyme will be valuable in the future studies concerned with Nitrogen metabolism in P. nigrum. Main objective of present study was to standardize the extraction and study the properties of GDH from P. nigrum L. Effect of additives and its optimum concentration were determined, standardized homogenizing medium was formulated, standardized assay system formulated, different properties like pH optimum, Substrate saturation and km value determined; it’s all in agreement with the previously reported values, result indicate NADP+/NADPH is the better substrate i.e. the enzyme activity is contributed by chloroplastic form of GDH than by the mitochondrial form.