The repressible alkaline phosphatase of Escherichia coli (orthophosphoric monoester phosphohydrolase, EC 3.1.3.1) promises to play a role in biochemical genetics comparable to that played by fl-galactosidase (l-5). It is also being used increasingly for class experiments. The evaluation of the important characteristic kinetic constants for this enzyme, however, poses certain technical difficult...

In this paper, we consider a competition model between n species in a chemostat including both monotone and non-monotone growth functions, distinct removal rates and variable yields. We show that only the species with the lowest break-even concentration survives, provided that additional technical conditions on the growth functions and yields are satisfied. We construct a Lyapunov function whic...

A particulate preparation obtained from Phoseolus aweus shoots contains an enzyme capable of transferring the 14Clabeled methyl groups from S-adenosyl-L-methionine to the carbozyl groups of polygalacturonic acid, which seems to be present in the same particulate material. The introduction of the methyl ester groups is optimal at pH 6.8 and does not require divalent ions. S-IV-Methyltetrahydrofo...

The parameters which characterize this equation, and which must ordinarily be estimated from the observed data, are ‘v,,,, the maximum initial velocity which is theoretically attained when the enzyme has been “saturated” by an infinite concentration of substrate, and K,, the Michaelis constant which is numerically equal to the concentration of substrate for half-maximal initial velocity. Since ...

A patient with an X-linked genetic disease resembling chronic granulomatous disease (CGD) but differing in several aspects from previously studied cases is described. The oxidase enzyme of the patient's granulocytes was normally activated, but had reduced activity as shown by an increased Michaelis constant and decreased maximum velocity of NADPH-dependent superoxide production. Cytochrome-b wa...

In this study, lipid-deprived residuals of microalgae were hydrolyzed for the production of reducing sugars by using the recombinant Bacillus cellulosome, carrying eight genes from the Clostridium thermocellum ATCC27405. The obtained cellulosome was found to exist mostly in the broth supernatant with a cellulosome activity of 2.4 U/mL. Furthermore, the Michaelis-Menten constant (Km) and Vmax of...

We study chemical reactions with complex mechanisms under two assumptions: (i) intermediates are present in small amounts (this is the quasi-steady-state hypothesis or QSS) and (ii) they are in equilibrium relations with substrates (this is the quasiequilibrium hypothesis or QE). Under these assumptions, we prove the generalized mass action law together with the basic relations between kinetic ...

238 / 250 Introduction: 453 / 750 Discussion: 1478 / 1500 Nonstandard abbreviations used are: Clint,app apparent intrinsic clearance; CYP, cytochrome P450; FMO, flavin-containing monooxygenase; HLM, human liver microsomes; HPLC, highperformance liquid chromatography; KM, Michaelis Menten constant; LC-MS, liquid chromatography mass spectrometry; MS, mass spectrometry; NMR, nuclear magnetic reson...

Phosphatidylethanolamine synthesis by CDP-ethanolamine:1,2-diacylglycerol ethanolaminephosphotransferase (EC 2.7.8.1) from the endoplasmic reticulum of castor bean (Ricinus communis L. var. Hale) endosperm was characterized. The Michaelis-Menten constant of the enzyme for CDP-ethanolamine was approximately 8.0 micromolar. The pH optimum was 6.5 and a divalent cation was an absolute requirement ...