title: A continuous method for enzymatic assay of sucrose synthase in the synthetic direction.
abstract: An appropriate method was developed for the continuous assay of sucrose synthase (SS) (EC 2.4.1.13) by spectrophotometry. The uridine 5'-diphosphate derived from sucrose synthesis was stoichiometrically coupled to oxidation of beta-nicotinamide adenine dinucleotide by the enzymes nucleoside-5'-diphosphate kinase (NDPK), pyruvate kinase, and lactate dehydrogenase. Utilization of crude extracts led to a complete masking of SS assay by adenylate kinase, adenosine 5'-triphosphatase (ATPase), and phosphoenolpyruvate phosphatase found in the crude extracts. These interfering enzymes were mostly removed from the crude extracts by using a combination of gel filtration, centrifugation through a selectively permeable membrane (Biomax-100 Ultrafree centrifugal device), and inhibition by the addition of K(2)HPO(4) to the assay buffer. Sensitivity of the SS assay was significantly increased by the inclusion of NDPK and ATP, which are essential to the reaction in the coupling system.
authors.affiliation: Department of Horticulture, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge, Louisiana 70803, USA. yhuang@agctr.lsu.edu
authors.forename: Y H
authors.initials: YH
authors.lastname: Huang
authors.forename: D H
authors.initials: DH
authors.lastname: Picha
authors.forename: A W
authors.initials: AW
authors.lastname: Kilili
mesh_terms: D005964:Glucosyltransferases / Q000032:analysis*; D007770:L-Lactate Dehydrogenase / Q000737:chemistry; D010084:Oxidation-Reduction; D011770:Pyruvate Kinase / Q000737:chemistry; D015203:Reproducibility of Results
chemical_list: D007770:L-Lactate Dehydrogenase; D005964:Glucosyltransferases; C022699:sucrose synthase; D011770:Pyruvate Kinase