Substrate regulation of System A-mediated amino acid transport was investigated in primary cultures of rat hepatocytes. Studies on the substrate specificity of trans-inhibition and repression revealed considerable differences between the two processes. Those data along with a difference in temperature sensitivity suggest that the two phenomena are not related or inter-dependent in any direct wa...

hydatid disease is a term used to refer infection with the methacestode of echinococcus granulosus parasite in humans, and echinococcusis is restricted to infection with the adult stage in carnivores.glutathione s-transferase (gst) represents the major class of detoxification enzymes from helminth parasites such as echinococcus protoscoleces (psc) and it is candidate for chemotherapeutic and va...

This investigation attempts to evaluate to what extent enzyme inhibition and repression by metabolites, indigenous to the cell, are significant phenomena in natural microbial communities. Three case histories of the kinetics of substrate utilization and growth in multisubstrate media by heterogeneous bacterial populations are presented: (i) concurrent substrate utilization and growth on both su...

A beta-glycosidase of a thermophile, Thermus thermophilus, belonging to the glycoside hydrolase family 1, was cloned and overexpressed in Escherichia coli. The purified enzyme (Ttbetagly) has a broad substrate specificity towards beta-D-glucoside, beta-D-galactoside and beta-D-fucoside derivatives. The thermostability of Ttbetagly was exploited to study its kinetic properties within the range 2...

The nature of strong negative cooperativity displayed by alkaline phosphatase from Escherichia coli was investigated by alternative substrate and product inhibition studies, and by catalytic rate constant (kcat) measurements. To see whether the idled subunit in this dimeric enzyme plays a mechanistic role in the overall catalysis, the flip-flop model proposed by Lazdunski et al. ((1971) Eur. J....

In the present work, kinetics of the biodegradation of benzene, toluene and phenol by using a pure culture of Pseudomonas putida (MTCC 1194) was determined by measuring the specific growth rate and degradation rate with substrate concentration as a function of time in a batch reactor. In general, the degradation rate of benzene, toluene and phenol increased with the increase in the initial subs...

DNA ligases are essential both to in vivo replication, repair and recombination processes, and in vitro molecular biology protocols. Prior characterization of DNA ligases through gel shift assays has shown the presence of a nick site to be essential for tight binding between the enzyme and its dsDNA substrate, with no interaction evident on dsDNA lacking a nick. In the current study, we observe...

Biodegradation kinetics were studied for binary and complex mixtures of nine polycyclic aromatic hydrocarbons (PAHs): Naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 2-ethylnaphthalene, phenanthrene, anthracene, pyrene, fluorene, and fluoranthene. Discrepancies between the observed biodegradation rates and those predicted by a sole-substrate model indicate that significant substrate inte...

Relatively few selective substrate and inhibitor probes have been identified for human UDP-glucuronosyltransferases (UGTs). This work investigated the selectivity of trifluoperazine (TFP), as a substrate, and amitriptyline, androsterone, canrenoic acid, hecogenin, phenylbutazone, quinidine, quinine, and sulfinpyrazone, as inhibitors, for human UGTs. Selectivity was assessed using UGTs 1A1, 1A3,...