The temperature dependence of the rate constant for substrate oxidation by the dehaloperoxidase-hemoglobin (DHP) of Amphitrite ornata has been measured from 278 to 308 K. The rate constant is observed to increase over this range by approximately a factor of 2 for each 10 °C temperature increment. An analysis of the initial rates using a phenomenological approach that expresses the peroxidase pi...

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 ...

Soybean lipoxygenase-1 kinetics are known to show product and substrate inhibition. With linoleic acid as the substrate and using a simple Michaelis-Menten formulation, we have shown that K(ss), the substrate inhibition constant was increased by more than five-fold when initial oxygen concentration was increased from 228 to 1140 microM. Excess substrate inhibition is in fact almost avoided at h...