Monoamine oxidase inhibition by nicotine and methomyl

Rabbit brain MAO [monoamine oxidase] is inactivated when incubated with some insecticides, nicotine [[S]-1-methyl-2-[3]-pyridyl] pyrrolidine] and methomyl, [1-methylthio] ethylidinamino-N- methylcarbamate]. The inhibition of the enzyme increased by increasing the concentration of these insecticides with TIC50 values equal to 3.3 muM and 4.4 muM concentration for nicotine and methomyl, respectively. Nicotine inhibited the rabbit brain MAO enzyme in a noncompetitive manner. Methomyl inhibited the enzymes in a competitive manner. The values of Km and Vmax, in the absence and presence of 2.5 muM of these insecticides, were determined. The results revealed that nicotine and methomyl are irreversible and nonselective MAO inhibitors

Inhibition of soybean lipoxygenase enzyme by trans-dichlorotetramethyl and ethylpyridine derivatives of cobalt [III] complexes

Soybean lipoxygenase is rapidly inactivated when incubated with trans-[Co [3-R-pyridine] 4Cl2] Cl [R is methyl [CMPC] or ethyl [CEPC] group]. The inhibition of the enzyme increased with increasing the concentration of these complexes with 150 values equal to 50 muM and 52 muM concentration for CMPC I and CEPC II, respectively. Lineweaver-Burk plots design showed that these complexes inhibit soybean lipoxygenase enzyme in a noncompetitive inhibition manner. The values of Km and Vmax, in the absence and presence of 33 muM of these complexes, were determined. The lipoxygenase enzyme is also inhibited by methylpyridine which is a precursor of CMPC I. This inhibition increased by increasing the concentration of methylpyridine

Lipoxygenase from Ulva lactuca [Ubvales, chloropyta]

Lipoxygenase enzyme [linoleate oxygen oxidoreductase EC 1.99.2.1] was separated and purified from the green alga Ulvalactuca by extraction of the cell-free extract, precipitation with 45% to 70% solid ammonium sulfate and chromatography on DEAE Sephadex A 50. This preparation has given two bands [Lipoxygenase 1 and 2] by disc gel electrophoresis. Lipoxygenase enzyme from Ulva has been obtained in 60% yield with specific activity in the range of 1262 n mol, hydroperoxylinoleate mg[-1]protein. A purification 63-fold was achieved from Ulva. The optimum pH of Ulva lipoxygenase is 8.0. The molecular weights of lipoxygenase 1 and 2 were 120000 and 103000 respectively. K[m]and V [max] were 307.6 uM and 250 n mol per mg protein ml[-1]min[-1] respectively. No unusual amino acids were detected by the amino acid analyser. There is no cystine in Ulva lipoxygenase. The iron content of the purified lipoxygenase enzyme was 1.05 ppm