A novel bromoperoxidase was isolated from the lichen Xanthoria parietina. The enzyme contained vanadium, which is essential for enzymic activity. Under denaturating conditions the preparation showed a single protein band with an Mr of 65,000. Thermal-denaturation studies showed that this bromoperoxidase could tolerate high temperatures. The affinity of the enzyme for its substrate bromide is hi...

We have studied membrane topology of cytochrome P-450c21 (P450c21) using the approaches of mutagenesis and protease digestion. P450c21 is located at the cytoplasm with an N-terminal hydrophobic domain integrated into microsomal membranes. When this hydrophobic domain was replaced by a secretory signal peptide, P450c21 was translocated into the lumen and lost enzymic activity. No other topogenic...

The intact diphtheria toxin molecule, a single polypeptide chain of about 62,000 daltons, has no enzymic activity. However, the transfer in uifro of ADP-ribose from NAD to aminoacyltrensferase II can be catalyzed by any of several fragments of toxin. The smallest active fragment (A, 24,000 daltons) is normally connected to the remainder of the molecule (B, 38,000 daltons) by a peptide bond and ...

Cytochemical methods have been used to examine the distribution of acid phosphatase, ribonuclease, esterase, amylase and protease activity and protein in the walls of pollen grains and spores. Enzyme activity was detected in the walls of 50 angiosperm pollens, in pine, and in the spore wall of a species of Equisetum. Activity was absent from the 2 species of ferns examined. The survey covered a...

An enzyme capable of hydrolyzing 4-methylumbelliferyl phenylphosphonate to 4-methylumbelliferone and phenylphosphonic acid has been detected in human serum. It has a Km value of 1.72 x 10(-4) mol/L, has an optimum pH of 8.8-9.1 in Tris buffer, and shows maximum activity at 60 degrees C (30 min). The enzymic activity can be inhibited by Na3PO4, EDTA, and cysteine. We saw no effect of CuSO4, aden...

Indole-3-acetic acid is oxidized to oxindole-3-acetic acid by Zea mays tissue extracts. Shoot, root, and endosperm tissues have enzyme activities of 1 to 10 picomoles per hour per milligram protein. The enzyme is heat labile, is soluble, and requires oxygen for activity. Cofactors of mixed function oxygenase, peroxidase, and intermolecular dioxygenase are not stimulatory to enzymic activity....

Esterolytic activity of three enzymic cholesterol reagents was evaluated with use of human serum-based reference materials. Primary cholesterol standards were used to calibrate the enzymic methods, and incomplete cholesteryl ester hydrolysis was measured as the bias between the enzymic cholesterol values and corresponding reference values. The average biases observed with eight reference specim...

Enzymic antioxidants were analyzed in both blue flowered leaf and white flowered leaf of Clitoria ternatea. The in vitro model used in the study as alternatives to live animals, was goat liver slices. The liver slices exposed to different treatments were incubated for one hour at 37 ̊C with very mild shaking. The enzymic antioxidant activity was analyzed by using goat liver slices, both blue flo...

The logistic temporal solution of the generalized Michaelis-Menten kinetics is employed to provide a quantum basis for the tunneling time and energy evaluations of Brownian enzymic reactions. The monosubstrate and mixed inhibition cases are treated and the associated quantum diagrams of the reaction mechanisms are depicted in terms of intermediate enzyme complexes. The methodology is suited for...