Biomaterial Database

Mechanism of inactivation of UDP-glucose 4-epimerase from Saccharomyces cerevisiae by D-xylose and L-arabinose. 1986

R S Cármenes, and S Gascón, and F Moreno

Departamento Interfacultativo de Bioquímica, Universidad de Oviedo, Spain.

In a previous paper (Cármenes et al., 1984) we reported that UDP-glucose 4-epimerase from Saccharomyces was inactivated both in vivo and in vitro (crude extracts) by L-arabinose or D-xylose. In this paper, we report that pure epimerase requires the presence of UMP or UDP to be inactivated by sugars and that the inactivation is due to the reduction of the epimerase NAD+, which is essential for epimerase activity. The inactivation rate is directly proportional to epimerase and sugar concentrations and hyperbolically proportional to UMP concentration. In situ experiments made with permeabilized cells showed that epimerase is inactivated in the same way when it is inside the cell. In vivo studies showed that epimerase is inactivated to a smaller extent when 1% D-galactose is present in the culture medium than when 1% ethanol is the main carbon source.

UI	MeSH Term	Description	Entries
D009243	NAD	A coenzyme composed of ribosylnicotinamide 5'-diphosphate coupled to adenosine 5'-phosphate by pyrophosphate linkage. It is found widely in nature and is involved in numerous enzymatic reactions in which it serves as an electron carrier by being alternately oxidized (NAD+) and reduced (NADH). (Dorland, 27th ed)	Coenzyme I,DPN,Diphosphopyridine Nucleotide,Nadide,Nicotinamide-Adenine Dinucleotide,Dihydronicotinamide Adenine Dinucleotide,NADH,Adenine Dinucleotide, Dihydronicotinamide,Dinucleotide, Dihydronicotinamide Adenine,Dinucleotide, Nicotinamide-Adenine,Nicotinamide Adenine Dinucleotide,Nucleotide, Diphosphopyridine
D010084	Oxidation-Reduction	A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).	Redox,Oxidation Reduction
D002238	Carbohydrate Epimerases	Enzymes that catalyze the epimerization of chiral centers within carbohydrates or their derivatives. EC 5.1.3.	Carbohydrate Isomerases,Epimerases, Carbohydrate,Isomerases, Carbohydrate
D003513	Cycloheximide	Antibiotic substance isolated from streptomycin-producing strains of Streptomyces griseus. It acts by inhibiting elongation during protein synthesis.	Actidione,Cicloheximide
D005690	Galactose	An aldohexose that occurs naturally in the D-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase (GALACTOSE-1-PHOSPHATE URIDYL-TRANSFERASE DEFICIENCY DISEASE) causes an error in galactose metabolism called GALACTOSEMIA, resulting in elevations of galactose in the blood.	D-Galactose,Galactopyranose,Galactopyranoside,D Galactose
D001089	Arabinose		L-Arabinose,L Arabinose
D012441	Saccharomyces cerevisiae	A species of the genus SACCHAROMYCES, family Saccharomycetaceae, order Saccharomycetales, known as "baker's" or "brewer's" yeast. The dried form is used as a dietary supplement.	Baker's Yeast,Brewer's Yeast,Candida robusta,S. cerevisiae,Saccharomyces capensis,Saccharomyces italicus,Saccharomyces oviformis,Saccharomyces uvarum var. melibiosus,Yeast, Baker's,Yeast, Brewer's,Baker Yeast,S cerevisiae,Baker's Yeasts,Yeast, Baker
D013050	Spectrometry, Fluorescence	Measurement of the intensity and quality of fluorescence.	Fluorescence Spectrophotometry,Fluorescence Spectroscopy,Spectrofluorometry,Fluorescence Spectrometry,Spectrophotometry, Fluorescence,Spectroscopy, Fluorescence
D014534	UDPglucose 4-Epimerase	A necessary enzyme in the metabolism of galactose. It reversibly catalyzes the conversion of UDPglucose to UDPgalactose. NAD+ is an essential component for enzymatic activity. EC 5.1.3.2.	UDP Galactose Epimerase,UDP Glucose Epimerase,UDPgalactose 4-Epimerase,Uridine Diphosphate Glucose Epimerase,UDP-Galactose 4-Epimerase,UDP-Glucose 4-Epimerase,4-Epimerase, UDP-Galactose,4-Epimerase, UDP-Glucose,4-Epimerase, UDPgalactose,4-Epimerase, UDPglucose,Epimerase, UDP Galactose,Epimerase, UDP Glucose,Galactose Epimerase, UDP,Glucose Epimerase, UDP,UDP Galactose 4 Epimerase,UDP Glucose 4 Epimerase,UDPgalactose 4 Epimerase,UDPglucose 4 Epimerase
D014542	Uridine Monophosphate	5'-Uridylic acid. A uracil nucleotide containing one phosphate group esterified to the sugar moiety in the 2', 3' or 5' position.	UMP,Uridylic Acid,Uridine 5'-Monophosphate,Uridylic Acids,5'-Monophosphate, Uridine,Acid, Uridylic,Acids, Uridylic,Monophosphate, Uridine,Uridine 5' Monophosphate