The mechanism of arginase activation has been widely studied during the past few years. Salaskin and Solowjew (1) and Waldschmidt-Leitz, Schaffner, and Kocholaty (2) believed that sulfhydryl compounds were the specific activators of arginase. This viewpoint was attacked by Edlbacher, Kraus, and Walter (3), and by Klein and Ziese (4), who presented evidence that the effect obtained with sulfhydr...

A sensitive, optimized assay for serum AMP deaminase (EC 3.5.4.6) is presented, which is based on a colorimetric indophenol determination of ammonia liberated during the enzyme reaction. An average enzyme activity in serum of 2.7 U/liter (n = 36, range 0-6.2) for healthy adults was established. Both the enzyme and colorimetric reactions were optimized to give an assay sensitivity of 0.2 U/liter...

Several Nox family NADPH oxidases function as multicomponent enzyme systems. We explored determinants of assembly of the multicomponent oxidases Nox1 and Nox3 and examined the involvement of Rac1 in their regulation. Both enzymes are supported by p47phox and p67phox or homologous regulators called Noxo1 and Noxa1, although Nox3 is less dependent on these cofactors for activity. Plasma membrane ...

The NADP+-dependent dehydrogenase activity of a predominant isoenzyme of human liver 3alpha-hydroxysteroid dehydrogenase was activated by antihyperlipidemic drugs, such as bezafibrate and clinofibrate, and by clofibric acid and fenofibric acid (active metabolites of clofibrate and fenofibrate, respectively). The optimal pH of the activation by the drugs was about 7.5, and the concentrations giv...

a naturally occurring plasma globulin, is converted by activators to plasmin, an enzyme which can digest many proteins, including fibrinogen and fibrin, prothrombin, factor V, and antihaemophilic globulin. Under physiological circumstances it is thought that natural inhibitors in the plasma restrict plasmin to digestion of fibrin, but in pathological fibrinolytic (hyperplasminaemic) states plas...

The properties of the endolysosomal enzyme GCase (glucosylceramidase), carrying the most prevalent mutation observed in Gaucher patients, namely substitution of an asparagine residue with a serine at amino acid position 370 [N370S (Asn370-->Ser) GCase], were investigated in the present study. We previously demonstrated that Sap (saposin) C, the physiological GCase activator, promotes the associ...

The presence of activators of the fibrinolytic system in blood plasma has been assumed for a long time but never convincingly documented by the isolation of characterized and physiologically plausible enzymes. The low catalytic efficiency of previously identified plasma plasminogen activators, which has made their physiological significance uncertain, prompted us to search for other plasma enzy...

PURPOSE Axonal damage and loss of neurons correlate with permanent vision loss and neurologic disability in patients with optic neuritis and multiple sclerosis (MS). Current therapies involve immunomodulation, with limited effects on neuronal damage. The authors examined potential neuroprotective effects in optic neuritis by SRT647 and SRT501, two structurally and mechanistically distinct activ...

We have demonstrated a lipid requirement for the UDPgalactose:1,2-diacylglycerol 3-beta-D-galactosyl-transferase (or monogalactosyldiacylglycerol synthase; EC 2.4.1.46), an enzyme involved in the biosynthesis of monogalactosyldiacylglycerol, solubilized from chloroplast envelope membranes and partially purified by hydroxyapatite chromatography. The enzyme fraction was highly delipidated (<0.1 m...