Résumé
We cloned 2-keto-3-deoxy-gluconate kinase (KDGK), which catalyzes the phosphorylation of 2-keto-3-deoxygluconate (KDG) to 2-keto-3-deoxy-6-phophogluconate (KDPG) from Serratia marcescens KCTC 2172. The nucleotide sequence revealed a single open reading frame containing 1,208 bp and encoding for 309 amino acids, with a molecular weight of 33,993 Da. The enzyme was purified via GST affinity chromatography. The putative KdgT binding site was detected upstream of the initial codon. The KDG kinase utilized 2-ketogluconate (KG) and KDG as substrates. The optimal temperature and pH for KDGK activity were 50ºC and 8.0, respectively.
Sujets)
Gluconates/métabolisme , Serratia marcescens/génétique , Serratia marcescens/métabolisme , Gelatinases/biosynthèse , Glutathione transferase/biosynthèse , Glutathione transferase/métabolisme , Triacylglycerol lipase/biosynthèse , Maltose/métabolismeRésumé
The thermophylic and cellulolytic fungus Humicola sp. secretes amylases in the liquid culture medium. This activity is induced by starch, maltose and cellobiose. Glucose impairs accumlation of amylolitic activity in the culture medium. The enzyme hydrolyzes starch, maltose and pullulan to glucose as the endproduct
Sujets)
Amylases/biosynthèse , Deuteromycota/enzymologie , Amidon/métabolisme , Cellobiose/métabolisme , Chromatographie sur couche mince , Milieux de culture , Glucose/métabolisme , Hydrolyse , Maltose/métabolisme , Deuteromycota/croissance et développement , Deuteromycota/métabolismeRésumé
The gastric emptying of maltose, sucrose, lactose and lactulose was compared in young adult ratswith ontogenic lactase deficiency. Eight animalswere employed for each sugar meal at each time od study (total number of animals = 192). Each animal received a test meal consisting of a solution of the sugar (100 mg/ml) and phenol red as marker and gastric retention was measured at 5,10,20,30,45 and 60 min after orogastric infusion of the test meal. Gastric retention was determined by measuring the concentration of the marker in the residual test meal recovered from the stomach after killing the animal. There was no difference between the gastric emptying of lactose and lactulose. The gastric emptying of maltose was significantly slower during the initial 30 min and the emptying of sucrose was identical to that of maltose only at 5 min and could not be distinguished from that oflactose and lactulose at later times. These data support the observation, made in human subjects, that under conditions of ontogenic lactase deficiency, the modulation of gastric emptying of lactose is ineffective. It is possible that the rapid emptying of sucrose is due to the saturation of sucrase because of substrate overload which impairs the intestinal inhibitory control of gastric emptying
Sujets)
Rats , Animaux , Mâle , Hydrates de carbone alimentaires/métabolisme , Diholoside/métabolisme , Vidange gastrique , Intolérance au lactose/métabolisme , Analyse de variance , Marqueurs biologiques , Ration calorique , Métabolisme énergétique , Lactose/métabolisme , Lactulose/métabolisme , Maltose/métabolisme , Lignées consanguines de rats , Saccharose/métabolisme , Facteurs tempsRésumé
1. The effects of catbolite inactivation upon the trehalose pathway linked to maltose utilization were investigated in Saccharomyces cerevisiae. Mutant strains devoid of UDPG-trehalose synthase activity were used in this study. 2. Trehalose accumulation was also susceptible to catabolite inactivation as has been reported for the carrier protein, one of the components of the maltose system. Reversibility was only achieved when incubation with glucose did not exceed 5 min and was dependent upon protein sunthesis