Purification and some properties of two NADP+-specific isocitrate dehydrogenases from an obligately psychrophilic marine bacterium, Vibrio sp., strain ABE-1

Journal of Biochemistry
T OchiaiS Sasaki

Abstract

Two isozymes of NADP+-specific isocitrate dehydrogenase [ICDH; EC 1.1.1.42] were confirmed to be present in an obligately psychrophilic marine bacterium, Vibrio sp., strain ABE-1, on the basis of the temperature-activity curve and electrophoretic mobilities. These isozymes were separated and purified about 170-fold for isozyme I (specific activity at 40 degrees C, 24.3 units/mg protein) and about 180-fold for isozyme II (specific activity at 20 degrees C, 59.2 units/mg protein), though the isozymes were still not homogeneous. The molecular weights of these isozymes determined by gel filtration were both about 85,000, but the properties of the isozymes were considerably different from each other. The thermostability of isozyme I resembled those of mesophiles, but isozyme II was extremely labile above 20 degrees C. NaCl affected the ICDH isozymes in different ways; the salt protected isozyme I from heat inactivation, but not isozyme II. Nevertheless it enormously enhanced the activity of isozyme II at low concentrations. Moreover, these ICDH isozymes showed different pH optima, Km values for isocitrate, susceptibilities to concerted inhibition by glyoxylate plus oxalacetate, and effects of 2-mercaptoethanol on their stabilities.

Citations

Apr 16, 2004·Extremophiles : Life Under Extreme Conditions·Seiji YamauchiHidenori Hayashi
Dec 20, 2005·Extremophiles : Life Under Extreme Conditions·Seiji YamauchiHidenori Hayashi
Jan 19, 2006·Extremophiles : Life Under Extreme Conditions·Shinsuke MakiYasuhiro Takada
Sep 21, 2011·Acta Crystallographica. Section D, Biological Crystallography·Navdeep S SidhuGeorge M Sheldrick
Apr 28, 2017·Extremophiles : Life Under Extreme Conditions·Ryo HirotaYasuhiro Takada
Jun 16, 2010·Archives of Microbiology·Shougo MatsuoYasuhiro Takada
Nov 1, 1991·The Journal of Applied Bacteriology·A M Gounot
Sep 27, 2008·Extremophiles : Life Under Extreme Conditions·Corien BakermansMichael F Thomashow

Related Concepts

Drug Stability
Isocitrate Dehydrogenase-I
Alloenzymes
NADP
Beneckea

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