The substrate depletion approach is an increasingly popular alternative to the traditional method (observing product formation) of determining the kinetic parameters (KM and Vmax) of an enzyme. Obach and Reed-Hagen (Drug Metab Dispos 30:831–837, 2002) used an empirical relationship between substrate depletion rate constants and initial substrate concentration to determine kinetic parameters for...

Phenytoin dosing is often difficult in a clinical situation because of the non-linear nature of phenytoin metabolism at therapeutic plasma concentrations. This study was performed to examine retrospectively five pharmacokinetic methods of adjusting phenytoin dosage based on a single steady-state plasma phenytoin concentration-dose pair in 66 epileptic Chinese children and adults. The methods co...

Rangoon creeper (Quisqualis indica Linn.) is a plant of the family Combretaceae. In Thai traditional medicine, its seeds contain oil and quisqualic acid that act as anthelminthic. Its flowers are used against diarrhea and eaten as vegetable. The flower extract gave high total polyphenol contents and showed strong antioxidant activity. In the search for new acetylcholinesterase inhibitors from p...

In the oyster Crassostrea gigas consumption-related traits, amylase properties and growth were found to be linked through genotypes that differed for polymorphism in the two amylase genes AMYA and AMYB. Modulation of AMYA mRNA level had already been observed in response to food availability, whereas the functional role of AMYB was still unknown. To improve knowledge about the regulation of amyl...

OBJECTIVE We previously reported that homocysteine (Hcy) inhibits endothelial cell (EC) growth and promotes vascular smooth muscle cell (VSMC) proliferation. This study characterized and directly compared Hcy transport in cultured human aortic ECs (HAECs) and smooth muscle cells (HASMCs). METHODS AND RESULTS Hcy (10 micromol/L) was transported into both cell types in a time-dependent fashion ...

A rat liver microsome pseudostationary phase has been used for the on-line capillary electrophoresis monitoring of glucuronidation. Uridine diphosphate glucuronosyltransferase (EC 2.4.1.17) containing microsomes was isolated from rat liver and directly injected onto neutrally coated capillary containing polymeric replaceable gels followed by injection of the substrate mixture. On-line glucuroni...

The working area of a screen-printed electrode, SPE, was modified with the enzyme tyrosinase (Tyr) using different immobilization methods, namely entrapment with water-soluble polyvinyl alcohol (PVA), cross-linking using glutaraldehyde (GA), and cross-linking using GA and human serum albumin (HSA); the resulting electrodes were termed SPE/Tyr/PVA, SPE/Tyr/GA and SPE/Tyr/HSA/GA, respectively. Th...

The substrate depletion approach is an increasingly popular alternative to the traditional method (observing product formation) of determining the kinetic parameters (KM and Vmax) of an enzyme. Obach and Reed-Hagen (Drug Metab Dispos 30:831–837, 2002) used an empirical relationship between substrate depletion rate constants and initial substrate concentration to determine kinetic parameters for...

Saccharomyces cerevisiae was obtained from palm wine and used for the extraction of peroxidase. Peroxidase isolated partially purified characterized. A twelve-day pilot study carried out which gave highest activity on day eight. The crude enzyme-specific –0.751 U/mg with 70% ammonium sulfate precipitation peroxidase achieved. precipitation, following gel filtration Sephadex G-100. Two peaks con...

Intravenous injections of n-propanol (25 mg, 50 mg, 100 mg, 200 mg, 300 mg) provoke blood concentration curves having exponential shapes of dose dependent rate constants after a sufficiently long time (2 min). They have to be seen therefore as a result of a non-linear elimination process controlled by a Michaelis-Menten-kinetic. Using the Lineweaver-Burk-method the characteristic data of metabo...