Studies on biosynthesis of coenzyme A in vitro by rat tissues.

Aiyar, A. S. and Sreenivasan, A. (1962) Studies on biosynthesis of coenzyme A in vitro by rat tissues. Indian Journal of Medical Research, 50. pp. 95-99.

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Abstract

THOUGH the biosynthesis of coenzyme A in microbial systems has been studied extensively, the biosynthesis in animal tissue preparations does not appear to have been investigated in detail (cf. Brown, 1959). No appreciable synthesis has as yet been reported in mammalian tissues in vitro, except in rat brain by Trufanov and Popova (1956). The occurrence of degradative enzymes and of cysteine desulfhydrase (Smythe, 1942) in mammalian tissues present obstacles, as there is rapid destruction of the endogenous as well as newly formed coenzyme A by the degradative enzymes and the cysteine desulfhydrase limits the availability of cysteine in the system. The report of hydroxylamine inhibiting the activity of cysteine desulfhydrase and its use in systems for the biosynthesis of glutathione from the component amino acids (Kasbekar, 1957) suggested the possibility of its use in following the biosynthesis of coenzyme A. The coenzyme A in blood appears to be localized mostly in the cells and no measurable amount is present in plasma (authors' observation with rat blood ; Kaplan and Lipmann, 1948. for human blood). There is also no evidence to indicate the permeability of erythrocyte membrane to coenzyme A of surrounding medium, and therefore, the hepatic origin of erythrocyte coenzyme A appears to be a remote possibility. Since erythrocytes have been shown to synthesize lipids (James et al., 1959 ; Rowe et al., 1960) and heme (London et al., 1950 ; Shemin et al., 1950 ; Dresel and Falk, 1956 ; Kassenaar et al., 1957) and to acetylate p-aminobenzoic acid (Blondheim, 1955) all of which require the participation of coenzyme A, it is to be expected that coenzyme A is a normal component of erythrocytes. These observations suggest the possibility of de novo synthesis of the coenzyme in erythrocytes. The ability of blood cells to synthesize other cofactors, e.g. flavin adenine dinucleotide from riboflavin (Klein and Kohn, 1940), pyridine nucleotides from nicotinamide (Leder and Handler, 1951), cocarboxylase from thiamine (Wooley, 1951) and citrovorum factor from folic acid (Mitbander and Sreenivasan, 1953) is also known. The biosynthesis of coenzyme A in vitro in liver homogenates, liver slices, brain homogenates and erythrocytes have been attempted and observations relating to the kinetics of the biosynthesis, the precursorial efficiency of various sulfhydryl compounds and the changes observed in these in pantothenic-acid deficiency are presented.

Item Type:	Article
Uncontrolled Keywords:	biosynthesis, coenzyme A, microbial systems
Subjects:	500 Natural Sciences and Mathematics > 07 Life Sciences > 03 Biochemistry & Molecular Biology > 07 Enzyme Biochemistry
Divisions:	Dept. of Biochemistry
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	12 Jul 2012 04:56
Last Modified:	12 Jul 2012 04:56
URI:	http://ir.cftri.res.in/id/eprint/5575

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