title: Cloning of beta-isopropylmalate dehydrogenase gene from Bacillus coagulans in Escherichia coli and purification and properties of the enzyme.
abstract: The beta-isopropylmalate dehydrogenase (2-hydroxy-4-methyl-3-carboxyvalerate: NAD+ oxidoreductase, EC 1.1.1.85) gene from Baccilus coagulans was cloned and expressed in Escherichia coli C600, using pBR322 as a vector plasmid. The B. coagulans enzyme was purified to a homogeneous state from the E. coli carrying a pBR322 - the B. coaglulans enzyme gene hybrid plasmid. The enzyme consists of two subunits of equal molecular weight (4.4 X 10(4) ). The enzyme activity was stimulated by 0.5 mM Mn2+, Mg2+ and Co2+. The enzyme was strongly inhibited by 0.2 mM p-chloromercuribenzoate and the inhibition was completely recovered by 1 mM dithiothreitol. The B. coagulans enzyme was thermostabilized by 1.5 M NaCl. The B. coagulans enzyme is a composite of alpha-helix, beta-sheet and remainder. The secondary structure of the enzyme was appreciably altered by 0.5 mM MgCl2 and 1.5 M NaCl.
mesh_terms: D050539:3-Isopropylmalate Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000235:genetics* / Q000302:isolation & purification; D001407:Bacillus / Q000201:enzymology*; D002412:Cations / Q000494:pharmacology; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D006358:Hot Temperature; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D011487:Protein Conformation
chemical_list: D002412:Cations; D000429:Alcohol Oxidoreductases; D050539:3-Isopropylmalate Dehydrogenase; D004262:DNA Restriction Enzymes