The kinetic mechanism of the sheep brain glutamine synthetase has been examined by both initial rate kinetics using the glutamate analog beta-glutamate and by isotope exchange measurements at equilibrium. Results of the initial rate studies were compatible with a number of sequential mechanisms but not with a partially or fully ordered rapid equilibrium or a ping-pong mechanism. Kinetic paramet...

Succinyl coenzyme A synthetase from Escherichia coli does not exhibit a steady state kinetic pattern indicative of “ping-pong” kinetics, despite the fact that catalytic participation of a phosphorylated enzyme covalent intermediate has been established. Instead, kineti.c patterns are consistent with the sequential addition of all substrates, to form a quaternary complex, before the release of a...

RNase H belongs to a nucleotidyl-transferase superfamily, which includes transposase, retroviral integrase, Holliday junction resolvase, and RISC nuclease Argonaute. We report the crystal structures of RNase H complexed with an RNA/DNA hybrid and a mechanism for substrate recognition and two-metal-ion-dependent catalysis. RNase H specifically recognizes the A form RNA strand and the B form DNA ...

ipa-43d is a hypothetical gene identified by the Bacillus subtilis genome project (Mol. Microbiol. 10, 371-384 1993; Nature 390, 249-256 1997). The ipa-43d protein overexpressed in E. coli was purified to homogeneity and its properties were analyzed biochemically. The ipa-43d protein was found to be tightly associated with FMN and to be capable of reducing both nitrofurazone and FMN effectively...

The natural maintenance cycles of many mosquito-borne pathogens require establishment of persistent non-lethal infections in the invertebrate host. The mechanism by which this occurs is not well understood, but we have previously shown that an antiviral response directed by small interfering RNAs (siRNAs) is important in modulating the pathogenesis of alphavirus infections in the mosquito. Howe...

The overall reaction catalysed by purified rat liver palmitoyl-CoA synthetase (EC 6.2.1.3) apparently proceeds via an enzyme-bound intermediate that may be either enzyme-fatty acyl-AMP (Berg, 1956), palmitate-enzyme-AMP, palmitate-enzyme-PP, or enzyme-palmitate. This conclusion is consistent with the following observations (Bar-Tana et al., 1973): (a) the initial velocity pattern of the overall...

Handover (HO) mechanism is one of the critical operations in Mobile WIMAX. It takes place when a mobile station (MS) moves from a serving base station (BS) to another BS.The handover procedure is comprised of several stages; network topology advertisement, MS scanning, cell selection, handover initiation and decision and network re-entry including ranging, authorization, authentication and re-r...

In this paper, we study the evolutionary Prisoner’s Dilemma Game (PDG) and the Snowdrift Game (SG) with a selfquestioning updating mechanism in the Barabási–Albert (BA) network. Although this self-questioning mechanism does not show much advantages in sustaining the cooperative behavior comparing to the existing models, it can produce interesting non-monotonic phenomena in numerical simulations...

The recombinant fructosyltransferase (Ftf) of Streptococcus salivarius was expressed in Escherichia coli and purified to electrophoretic homogeneity after a combination of adsorption, ion-exchange and gel-filtration chromatography. The N-terminal signal sequence of the Ftf was removed by E. coli at the same site as in its natural host. The purified Ftf exhibited maximum activity at pH 6.0 and 3...

An efficient enzyme kinetics assay using electrospray ionization mass spectrometry (ESI-MS) was initially applied to the catalytic mechanism investigation of a carbohydrate sulfotransferase, NodST. Herein, the recombinant NodST was overexpressed with a His(6)-tag and purified via Ni-NTA metal-affinity chromatography. In this bisubstrate enzymatic system, an internal standard similar in structur...