Microsomal epoxide hydrolase, a major antigenic marker of putative preneoplastic hepatocytes was studied in hyperplastic liver nodules and in normal liver tissue. Hyperplastic nodules induced by two different protocols contained 2to 3-fold higher specific activities of microsomal epoxide hydrolase than did normal surrounding tissue. However, no increase in cytosolic epoxide hydrolase determined...

Microsomal fractions isolated from pancreatic islet cells were shown to contain high specific glucose-6-phosphatase activity. The islet-cell glucose-6-phosphatase enzyme has the same Mr (36,500), similar immunological properties and kinetic characteristics to the hepatic microsomal glucose-6-phosphatase enzyme.

Yellow dent, high amylose and waxy corn were evaluated using lab-scale conventional, enzymatic (E-milling) intermittent milling dynamic steeping (IMDS) processes. The application of proteolytic enzyme sulfur dioxide (Conventional IMDS process) during kernel hydration their effects on overall starch yields from three types studied. Despite lower amount SO2 (600 ppm) shorter duration (66.8%), E-m...

1. The inactivation of phosphoenolpyruvate carboxykinase (GTP) (EC 4.1.1.32) in liver extracts was catalysed by the microsomal fraction, and led to the enzyme becoming bound to the microsomal membranes. 2. Inactivation by microsomal fraction, typsin or heating at 48degreesC was accelerated by L-cystine, D-cystine and oxidized glutathione and decreased by dithiothreitol. 3. MnC1(2) and CoC1(2) p...

Peroxynitrite (ONOO-) toxicity is associated with protein oxidation and/or tyrosine nitration, usually resulting in inhibition of enzyme activity. We examined the effect of ONOO- on the activity of purified rat liver microsomal glutathione S-transferase (GST) and found that the activity of reduced glutathione (GSH)-free enzyme was increased 4- to 5-fold by 2 mM ONOO-; only 15% of this increased...

The aim of the present study was to characterize the acyl-coenzyme A: cholesterol acyltransferase (ACAT) activity in human liver microsomes. Liver biopsies were obtained from patients undergoing elective cholecystectomy under highly standardized conditions. In 34 patients the enzyme activity of the microsomal fraction averaged 6.6 +/- 0.7 (mean +/- SEM) pmol.min-1.mg protein-1 in the absence of...

1. Tyrosine aminotransferase from guinea-pig liver is inactivated at neutral pH by a factor localized in the microsomal fraction. The inactivation, independent of exogenous L-cysteine, is rapidly reversed by addition of dithiothreitol. 2. The effects of physiological reducing agents on the enzyme inactivation were investigated. L-Cysteine and L-cysteamine enhance the inactivation rate of the en...