Studies on nucleotidases in plants Dimerization of the crystalline mung bean nucleotide pyrophosphatase by 5-adenosine monophosphate and the properties of the dimerized enzyme

Balakrishnan, CV and Ravindranath, SD and Rao, N Appaji (1975) Studies on nucleotidases in plants Dimerization of the crystalline mung bean nucleotide pyrophosphatase by 5-adenosine monophosphate and the properties of the dimerized enzyme. In: Archives of Biochemistry and Biophysics, 168 (1). 163 -170.

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Abstract

The addition of AMP to the crystalline and homogeneous mung bean nucleotide pyrophosphatase [EC 3.6.1.9]altered its electrophoretic mobility. AMP was tightly bound to the enzyme and was not removed on passage through a column of Sephadex G-25 or on electrophoresis. The molecular weight of the native and AMP-modified enzymes were 65,000 and 136,000, respectively. The properties of the native enzyme such as the pH (9.4) and temperature (49 °C) optima, inhibition by EDTA, reversal of EDTA-inhibition by Zn2+ and Co2+, were not altered on dimerization by AMP. The AMP-modified enzyme had a linear time-course of reaction, unlike the native enzyme which exhibited a biphasic time-course of reaction. The AMP-modified enzyme was irreversibly denatured by urea. AMP concentrations larger than 100 μM inhibited linearly the activity of the AMP-modified enzyme. ADP and ATP inhibited the activity in a sigmoidal manner. Km and V of the native and AMP-modified enzymes were, 0.25 mImage and 0.58 mImage ; and 3.3 and 2.5, respectively.

Item Type:	Journal Article
Publication:	Archives of Biochemistry and Biophysics
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	27 Jan 2010 10:33
Last Modified:	19 Sep 2010 05:49
URI:	http://eprints.iisc.ac.in/id/eprint/24135

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