For bovine erythrocyte acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7), the Michaelis parameters Vmax., and Km for the natural substrate acetylcholine were estimated as a function of pH and sodium chloride concentration by the pH-stat method. A single dissociation constant for Na+ binding (K = 7 X 10(-3) M) suffices to explain the salt dependence of Vmax./Km and of Km as well as the ...

Decomposition of soil organic matter (SOM) is mediated by microbial extracellular hydrolytic enzymes (EHEs). Thus, given the large amount of carbon (C) stored as SOM, it is imperative to understand how microbial EHEs will respond to global change (and warming in particular) to better predict the links between SOM and the global C cycle. Here, we measured the Michaelis–Menten kinetics [maximal r...

Both ritonavir and indinavir were readily metabolized by human intestinal microsomes. Comparison of the patterns of metabolites in incubations with enterocyte microsomes and expressed cytochrome P450 (CYP) isozymes and immunoinhibition and chemical inhibition studies showed the essential role of the CYP3A subfamily in the metabolism of both protease inhibitors by the small intestine. Ritonavir ...

The hydrolysis of adenosine 3':5'-monophosphate by the high Km cyclic nucleotide phosphodiesterase of bakers' yeast was studied over a range of temperature and pH at I = 0.17. The effects of ionic strength and MgCl2 concentration were studied at pH 7.7 and 30 degrees C. Km and Vmax were insensitive to changes in the MgCl2 concentration between 1 and 30 mM, implying that this enzyme (which does ...

background and objective: artimisinin (an anti-malaria drug) is extracted from artemisia annua and its water soluble derivative is dihydroartimisinin. previous in vivo and in vitro studies showed that it has an inhibitory effect on t cells. it is also useful for immunosuppression of immune system. materials and methods: the stable state kinetic for comparison of inhibitory effect of artimisinin...

Background: Acid phosphatase (ACP) is suggested to be one of the virulence factors in leishmania and a correlation has been reported between Leishmanial acid phosphatase (ACP) activity and the severity of the disease in all types of leishmaniasis including zoonotic cutaneous leishmaniasis (ZCL), which is a polymorphic disease. Objective: Characterization of leishmania and its correlation with t...

The kinetic constants of the site-specific endonuclease, ScaI, for various substrates were determined. We estimated Vmax and Km for octa-, deca-, dodeca-, and hexadecanucleotides and for plasmid pBR322 DNA. Vmax for these substrates were close, but Km were quite different (in decreasing order, octa- greater than deca-, dodeca-, hexadeca- greater than pBR322). The results were discussed with res...

objective(s): enzyme immobilization via nanoparticles is perfectly compatible against the other chemical or biological approximate to improve enzyme functions and stability. in this study lactoperoxidase was immobilized onto silica-coated magnetite nanoparticles to improve enzyme properties in the presence of cadmium chloride as an inhibitor. materials and methods:  the process consists of the ...

We examined the effects of alloxan-diabetes on the kinetic properties of the soluble and the membrane-bound forms of acetylcholinesterase (AChE) in rat brain. The Km (0.15 mM) and Vmax. (1.5 mmol/min per mg of protein) of the soluble form of the enzyme were unchanged in the diabetic animals. The membrane-bound enzyme in the control group displayed a lower Km (0.09 mM) and a higher Vmax. (7.2 mm...