alkaline phosphatase closely resembled that extracted from microsomes of human liver in some physicochemical respects. The specific activities of these enzymes in the complex were found to be of similar order of magnitude as compared with those of the same enzymes in plasma membranes isolated from the human liver. From the precipitate formed by incubating the complex with its antibody, all the ...

( Asymmetric cellulose acetate membranes have been prepared and characterized in the laboratory with a view to use them in membrane bio-reactors. Enzymatic hydrolysis of sucrose has been investigated in a dead-end stirred cell type membrane bio-reactor using these membranes. Effect of different operating variables such as substrate concentration, enzyme loading, flow rate and working volume hav...

The transverse distribution of enzyme proteins and phospholipids within microsomal membranes was studied by analyzing membrane composition after treatment with proteases and phospholipases. Upon trypsin treatment of closed microsomal vesicles, NADH- and NADPH-cytochrome c reductases as well as cytochrome b5 were solubilized or inactivated, while cytochrome P-450 was partially inactivated. When ...

Chalcone synthase [naringenin-chalcone synthase; malonyl-CoA:4-coumaroyl-CoA malonyltransferase (cyclizing), E.C. 2.3.1.74], the key enzyme of flavonoid pathways that was believed to be soluble, has been localized on ribosome-bearing endoplasmic reticulum membranes in the epidermis of buckwheat (Fagopyrum esculentum M.) hypocotyls. Enzyme activity measurement and immunoblots of buckwheat hypoco...

Ca2(+)-ATPase activity in human red cell membranes is dependent on the presence of calmodulin. All trans-retinoic acid inhibited human red cell membrane Ca2(+)-ATPase activity in vitro in a concentration-dependent manner (10(-8) to 10(-4) M). In contrast, retinol, retinal, 13-cis-retinoic acid and the benzene ring analogue of retinoic acid did not alter enzyme activity. Purified calmodulin (up ...

Incubation of rat fat pad membranes with 5-guanylyliminodiphosphonate [Gpp-(NH)p] and 5-guanylylmethylenediphosphonate [Gpp(CH2)p], but not GTP (with or without hormones), at 24 degrees or 30 degrees (but not at 4 degrees) greatly stimulates adenylate cyclase activity [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] measured after thoroughly washing the membranes. The rate of activation is rel...

Serum containing normal and abnormal levels of alkaline phosphatase activity were assayed for total enzyme activity, then fractionated by electrophoresis on cellulose acetate membranes for 20 mm. The new substrate, phenolphthalein monophosphate, was employed to locate the isoenzymes on the cellulose acetate membranes and to measure their activity by eluting and scanning procedures. The sensitiv...

Membrane-bound L-lactate dehydrogenase was solubilized from the membranes ofEscherichia coli and purified to homogeneity using conventional procedures. The enzyme had a pH optimum of 8 to 9 and was specific for L-lactate. Its apparent K, for L-lactate and maximal velocity were 1.2 x lo-’ M and 31 pmol of tetrazolium dye reducedlminlmg of protein, respectively. It had a polypeptide molecular wei...

Among the recognized morphological features of cells, the esternal membrane is one of the most poorly understood in terms of both structure and function, especially with regard to its participation in transport processes. In recent years, the chemical and enzymatic composition of isolated cell membranes from a few species of bacterial organisms have received the attention of a number of investi...

N-Arachidonylethanolamine (AEA), a putative endogenous agonist of neuronal (CB1) cannabinoid receptors, is a substrate for N-arachidonylethanolamine amidohydrolase (AEA amidohydrolase), a serine amidase present in cell membranes. Following a strategy that has been used to develop inhibitors that covalently bind to the active site of serine peptidases, diazomethyl arachidonyl ketone (DAK) was sy...