Endothelium-dependent vasodilation is impaired in patients with essential hypertension. The objective of this study was to determine whether long-term treatment with angiotensin-converting enzyme inhibitors improves endothelium-dependent vasodilation in forearm resistance vessels of patients with hypertension. Furthermore, since tissue thiols may be relevant to nitric oxide-mediated vasodilatio...

1. The reaction of mitochondrial adenosine triphosphatase (coupling factor 1) with iodine resulted in rapid loss of ATPase activity, disappearance of sulfhydryl groups, binding of iodine to the protein, and partial dissociation of the molecule. The extent of the changes observed depended on the molar ratio of iodine to protein in the reaction mixture. At a molar ratio of 50, more than 99% of th...

Threonine deaminase (Lthreonine hydrolyase (deaminating), EC 4.2.1.16) has been purified approximately 700-fold from extracts of Clostridium tetanomorphum. Both threonine and serine can serve as substrates, but threonine is deaminated 5 to 10 times more rapidly than serine. Pyridoxal phosphate, a reducing agent, and alkaline pH are required for the deamination of either amino acid. A plot of th...

Chicken pepsinogen was extracted from the forestomach of chicken and purified by the consecutive application of acetone precipitation, chromatography on diethylaminoethyl cellulose, and gel filtration on Sephadex G-100. The purified pepsinogen was homogeneous on disc electrophoresis and sedimented as monodisperse material. Chicken pepsin was obtained by the activation of the pure zymogen at pH ...

with n-heptyl-fi-D-thioglucoside, and then purified by DEAE-Sepharose and hydroxylapatite columns containing Triton X-100. The puTified enzyme was electrophoretically homogeneous. The enzyme had an apparent molecular mass of 400kDa, and was composed of three subunits whose molecular masses were 74, 70, and 62 kDa. The purified enzyme was much more labile than the membrane-bound enzyme (membrane...

The exudate of fully germinated spores of Clostridium perfringens was found to contain a large amount of a spore lytic enzyme which acted directly on alkali-treated spores of the organism to cause germination. Although no detectable amount of the enzyme was found in dormant spores during germination in a KCl medium, the enzyme was produced rapidly and released into the medium. The optimal condi...

The functional significance of the oxidation/reduction state of sulfhydryl groups of cGMP-dependent protein kinase (cGMP kinase) was studied at 30 degrees C using different metal ions as oxidizing agents. Mn2+, Zn2+, Fe2+, Ni2+, and Co2+ failed to activate cGMP kinase, whereas Cu2+, Cu+, Fe3+, Hg2+, and Ag+ activated cGMP kinase by oxidation with an activity ratio (-cGMP/+cGMP) of about 0.7. Th...

Thiaminases, enzymes that cleave vitamin B1, are sporadically distributed among prokaryotes and eukaryotes. Thiaminase I enzymes catalyze the elimination of the thiazole ring moiety from thiamin through substitution of the methylene group with a nitrogenous base or sulfhydryl compound. In eukaryotic organisms, these enzymes are reported to have much higher molecular weights than their bacterial...

Fully reduced ribonuclease (RNase), devoid of demonstrable secondary or tertiary structure, may be oxidized by molecular oxygen to yield a product which is indistinguishable by physical measurements or enzymatic activity from the native enzyme (2-4). Since reduced RNase contains eight sulfhydryl groups, 105 possible arrangements with four disulfide bridges may occur (5, 6), yet the native enzym...

The sulfhydryl enzyme malate synthase was inactivated by X-irradiation in air-saturated aqueous solution, in the absence or presence of a variety of additives (thiols, antioxienzymes, typical radical scavengers, inorganic salts, buffer components, substrates, products, analogues). Radiation-induced changes of enzymic activity were registered immediately after stop of irradiation and in the post...