title: Adenosine 5'-pyrophosphate sulphurylase in baker's yeast.
abstract: ADP sulphurylase from baker's yeast was purified and its properties were studied. The enzyme is very heat-labile and its activity shows linear kinetics over narrow ranges of time and protein concentration. It is not activated by metals and is inhibited by thiol-reactive compounds. The enzyme, which replaces inorganic sulphate in adenosine 5'-sulphatophosphate with P(i) to yield ADP, also catalyses an exchange of P(i) into ADP. Kinetic studies show that the enzyme has a high affinity for adenosine 5'-sulphatophosphate, although concentrations in excess of 1.0mm are inhibitory. However, the kinetics for P(i) are more complex and the enzyme is not inhibited by P(i) up to 20.0mm.
mesh_terms: D000244:Adenosine Diphosphate; D002729:Chloromercuribenzoates / Q000494:pharmacology; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000378:metabolism; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008670:Metals; D009713:Nucleotidyltransferases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013431:Sulfates / Q000378:metabolism; D013997:Time Factors
chemical_list: D002729:Chloromercuribenzoates; D005656:Fungal Proteins; D008670:Metals; D010710:Phosphates; D013431:Sulfates; D000244:Adenosine Diphosphate; D009713:Nucleotidyltransferases