title: Physical properties and metabolite regulation of ribulose bisphosphate carboxylase from Thiobacillus A2.
abstract: Purified ribulose-bisphosphate carboxylase (EC 4.1.1.39) was strongly and equally inhibited either by ADP or GDP and to a lesser extent by IDP. AMP or ATP exerted little effect on activity. Inhibition by the nucleotide diphosphates was competitive with respect to RuBP and non-competitive with respect to "CO2" and Mg2+, respectively. Treatment of the enzyme with urea or guanidine-HCl resulted in rapid loss of activity that was not restored by dialysis even in the presence of Mg2+ and cysteine. Sodium dodecyl sulfate electrophoresis of 8.0 M urea treated enzyme revealed the presence of a fast-moving (small) sub-unit with molecular weight 14150 and a slower moving (large) sub-unit with molecular weight 68000. Examination of native enzyme by sodium dodecyl sulfate electrophoresis gave sub-units of 13700 and 55500 respectively. The amino acid content standardized to phenylalanine was essentially similar to that from other sources. Arrhenius plots showed a "break" at 29 degrees C with an Ea of 12.34 kcal per mole for the steeper part of the curve and a deltaH of 11.43 kcal per mole while for the less steep region, the Ea was 1.04 kcal per mole and the deltaH 1.92 kcal per mole.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D002245:Carbon Dioxide / Q000378:metabolism; D002262:Carboxy-Lyases / Q000032:analysis*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D006146:Guanidines / Q000494:pharmacology; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism; D008970:Molecular Weight; D011685:Purine Nucleotides / Q000494:pharmacology; D012273:Ribulose-Bisphosphate Carboxylase / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000378:metabolism; D013696:Temperature; D013855:Thiobacillus / Q000201:enzymology*; D014508:Urea / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D006146:Guanidines; D011685:Purine Nucleotides; D002245:Carbon Dioxide; D014508:Urea; D002262:Carboxy-Lyases; D012273:Ribulose-Bisphosphate Carboxylase; D008274:Magnesium