Gupta, MKale, R K1996-10-012009-05-271996-10-012009-05-271996-10-01Gupta M, Kale RK. Influence of Ca2+ on kinetics and thermodynamics of the NADPH-dependent microsomal lipid peroxidation. Indian Journal of Biochemistry & Biophysics. 1996 Oct; 33(5): 377-83http://imsear.searo.who.int/handle/123456789/28351The effect of Ca2+ on kinetics and thermodynamics of lipid peroxidation in microsomes prepared from liver of male Swiss albino mice (7-8 weeks old) was studied. Ca2+ was found to increase the Vmax in temperature dependent manner. Michaelis-Menten constant (Km) also increased with temperature. However, the linearity and extent of change in Km remained unaffected in presence of Ca2+, and was suggestive of non-competitive and mixed type of activation. The activation constant (Ka) obtained by the replotting of slopes of the Lineweaver-Burk plots against the reciprocal of Ca2+ concentration showed linear variation with temperature. The linear pattern of Arrhenius plots indicated non-involvement of parallel reactions of other intermediate species in the lipid peroxidation. Thermodynamic parameters delta H degree, delta S degree and delta G degree, associated with lipid peroxidation process were studied. The positive value of delta H degree is suggestive of the endothermic nature of the process. It appears that the NADPH induced lipid peroxidation is an entropy driven process.engAnimalsCalcium --pharmacologyKineticsLipid Peroxidation --drug effectsMaleMiceMicrosomes, Liver --drug effectsNADP --metabolismNADPH-Ferrihemoprotein Reductase --metabolismThermodynamicsIn Vitro