title: Studies on substrate specificity and activity regulating factors of trehalose-6-phosphate synthase of Saccharomyces cerevisiae.
abstract: Purified trehalose-6-phosphate synthase (TPS) of Saccharomyces cerevisiae was effective over a wide range of substrates, although differing with regard to their relative activity. Polyanions heparin and chondroitin sulfate were seen to stimulate TPS activity, particularly when a pyrimidine glucose nucleotide like UDPG was used, rather than a purine glucose nucleotide like GDPG. A high V(max) and a low K(m) value of UDPG show its greater affinity with TPS than GDPG or TDPG. Among the glucosyl acceptors TPS showed maximum activity with G-6-P which was followed by M-6-P and F-6-P. Effect of heparin was also extended to the purification of TPS activity, as it helped to retain both stability and activity of the final purified enzyme. Metal co-factors, specifically MnCl(2) and ZnCl(2) acted as stimulators, while enzyme inhibitors had very little effect on TPS activity. Metal chelators like CDTA, EGTA stimulated enzyme activity by chelation of metal inhibitors. Temperature and pH optima of the purified enzyme were determined to be 40 degrees C and pH 8.5 respectively. Enzyme activity was stable at 0-40 degrees C and at alkaline pH.
authors.affiliation: Biotechnology Division, Indian Institute of Chemical Biology, Kolkata 700 032, India.
authors.forename: Paramita
authors.initials: P
authors.lastname: Chaudhuri
authors.forename: Arghya
authors.initials: A
authors.lastname: Basu
authors.forename: Shinjinee
authors.initials: S
authors.lastname: Sengupta
authors.forename: Sagar
authors.initials: S
authors.lastname: Lahiri
authors.forename: Trina
authors.initials: T
authors.lastname: Dutta
authors.forename: Anil K
authors.initials: AK
authors.lastname: Ghosh
mesh_terms: D002614:Chelating Agents / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005636:Fructosephosphates / Q000378:metabolism; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D005964:Glucosyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D006493:Heparin / Q000494:pharmacology; D007535:Isomerases / Q000378:metabolism; D008360:Mannosephosphates / Q000378:metabolism; D008670:Metals / Q000494:pharmacology; D000071228:Polyelectrolytes; D011108:Polymers / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology*; D013379:Substrate Specificity / Q000187:drug effects
chemical_list: D002614:Chelating Agents; D004791:Enzyme Inhibitors; D005636:Fructosephosphates; D005954:Glucosephosphate Dehydrogenase; D005964:Glucosyltransferases; D006493:Heparin; D007535:Isomerases; D008360:Mannosephosphates; D008670:Metals; D000071228:Polyelectrolytes; D011108:Polymers; C027693:mannose-6-phosphate; C027618:fructose-6-phosphate; C023180:trehalose-6-phosphate synthase