Intact bovine fibroblasts, pericytes, and kidney cells manifested significantly less tissue factor procoagulant activity than their disrupted counterparts. Addition of calcium ionophore A23187 rapidly and reversibly enhanced the cell-surface expression of tissue factor in intact cells up to the level achieved by disruption. Inhibitors of calmodulin blocked the ionophore-dependent enhancement of...

Highly polymerized herring testis DNA of the random nucleotide sequence was used as a model of natural substrate to study some features of hydrolysis of the hybrid B-Z form with Serratia marcescens nuclease. The hybrid B-Z form was formed upon addition of 1.15 M MgSO4 and 0.421 mM Co(NH3)6Cl3. The DNA transition from the right handed B-form to the hybrid B-Z-form caused a decrease in Vmax of DN...

Can a queuine-specific tRNA function normally without replacement of G by Q in its structure? To answer this, kinetics of aspartate queuine-containing tRNA (Q-tRNA) is compared with its queuine-deficient counterpart (G-tRNA). The results indicate that Asp Q-tRNA is a more effective substrate than the Asp G-tRNA. The Asp Q-tRNA exhibits a higher reaction velocity (Vmax greater than 30%) and a hi...

The mouse Na+/taurocholate cotransporting polypeptide transiently expressed in COS-7 cells caused sodium-dependent uptake of [3H]taurocholic acid with Km and Vmax values of 18 microM and 102 pmol/mg protein/min, respectively. This Km value is comparable to that for rat NTCP and higher than that for human NTCP. Substrate specificity was evaluated by measuring inhibitory effects of unlabeled bile...

Stimulation of human platelet adenylate cyclase by the diterpene forskolin is associated with a decrease in the apparent substrate (MgATP) affinity of the enzyme. Addition of the stimulatory hormone prostaglandin E1 not only further increased the Vmax. of the forskolin-stimulated platelet adenylate cyclase but also caused a further increase in the Km value for MgATP, by up to 20-fold compared w...

Substrate kinetic properties of cytochrome oxidase in rat liver, kidney, brain and heart mitochondria were examined using ascorbate + N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) as the electron donor system. Analysis of the substrate kinetics data revealed tissue-specific expression of kinetic components exhibiting differences with respect to Km, Vmax and Kcat/Km values. Regression analysis...

abstract kinetic properties of root of peroxidase of gundelia tournefortii investigated at different ph, temperature and different inhibitors. maximum activity of peroxidase achieved at ph 5.5-6 in according to type of substrate. activity of peroxidase increased at constant concentration of h2o2 and different concentration of guaiacol, catechol and pyrogallol. the maximum activity in presence o...

The kynureninase-type enzymes of three fungi and one bacterium were isolated and examined kinetically for their ability to catalyze the hydrolysis of L-kynurenine and L-3-hydroxykynurenine. The phycomycete Rhizopus stolonifer was found to contain a single, constitutive enzyme with Km for L-3-hydroxykynurenine and L-kynurenine of 6.67 times 10-minus 6 and 2.5 times 10-minus 4 M, respectively. Th...