title: Cooperative binding of substrates to transketolase from Saccharomyces cerevisiae.
abstract: Catalytic activity of two active sites of transketolase and their affinity towards the substrates (xylulose-5-phosphate and ribose-5-phosphate) has been studied in the presence of Ca2+ and Mg2+. In the presence of Ca2+, the active sites exhibit negative cooperativity in binding both xylulose-5-phosphate (donor substrate) and ribose-5-phosphate (acceptor substrate) and positive cooperativity in the catalytic transformation of the substrates. In the presence of Mg2+, nonequivalence of the active sites is not observed.
authors.affiliation: Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
authors.forename: I A
authors.initials: IA
authors.lastname: Sevostyanova
authors.forename: V A
authors.initials: VA
authors.lastname: Selivanov
authors.forename: V A
authors.initials: VA
authors.lastname: Yurshev
authors.forename: O N
authors.initials: ON
authors.lastname: Solovjeva
authors.forename: S V
authors.initials: SV
authors.lastname: Zabrodskaya
authors.forename: G A
authors.initials: GA
authors.lastname: Kochetov
mesh_terms: D020134:Catalytic Domain; D007700:Kinetics; D010428:Pentosephosphates / Q000378:metabolism; D012267:Ribosemonophosphates / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism; D013379:Substrate Specificity; D014174:Transketolase / Q000737:chemistry* / Q000378:metabolism
chemical_list: D010428:Pentosephosphates; D012267:Ribosemonophosphates; D029701:Saccharomyces cerevisiae Proteins; C031626:ribose-5-phosphate; C031625:xylulose-5-phosphate; D014174:Transketolase