Arginine Decarboxylase from Lathyrus sativus Seedlings Purification and Properties

Ramakrishna, Seethala and Adiga, Radhakantha P (1975) Arginine Decarboxylase from Lathyrus sativus Seedlings Purification and Properties. In: European Journal of Biochemistry, 59 (2). 377 -386.

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Abstract

Arginine decarboxylase which makes its appearance in Lathyrus sativus seedlings after 24 h of seed germination reaches its highest level around 5–7 days, the cotyledons containing about 60% of the total activity in the seedlings at day 5. The cytosol enzyme was purified 977-fold from whole seedlings by steps involving manganese chloride treatment, ammonium sulphate and acetone fractionations, positive adsorption on alumina C-γ gel, DEAE-Sephadex chromatography followed by preparative disc gel electrophoresis. The enzyme was shown to be homogeneous by electrophoretic and immunological criteria, had a molecular weight of 220000 and appears to be a hexamer with identical subunits. The optimal pH and temperature for the enzyme activity were 8.5 and 45 °C respectively. The enzyme follows typical Michaelis-Menten kinetics with a Km value of 1.73 mM for arginine. Though Mn2+ at lower concentrations stimulated the enzyme activity, there was no dependence of the enzyme on any metal for the activity. The arginine decarboxylase of L. sativus is a sulfhydryl enzyme. The data on co-factor requirement, inhibition by carbonyl reagents, reducing agents and pyridoxal phosphate inhibitors, and a partial reversal by pyridoxal phosphate of inhibition by pyridoxal · HCl suggests that pyridoxal 5'-phosphate is involved as a co-factor for the enzyme. The enzyme activity was inhibited competitively by various amines including the product agmatine. Highest inhibition was obtained with spermine and arcain. The substrate analogue, l-canavanine, homologue l-homoarginine and other basic amino acids like l-lysine and l-ornithine inhibited the enzyme activity competitively, homoarginine being the most effective in this respect.

Item Type:	Journal Article
Publication:	European Journal of Biochemistry
Publisher:	John Wiley and Sons
Additional Information:	Copyright of this article belongs to John Wiley and Sons.
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	23 Oct 2009 04:35
Last Modified:	01 Mar 2012 06:46
URI:	http://eprints.iisc.ac.in/id/eprint/23784

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