A new rapid assay for phosphatidylserine decarboxylase, which is sensitive in the nanomolar range, is described. Synthesis of radiolabeled phosphatidylserine for use as a substrate is not required, since the assay, unlike previous ones, is based on the detection of CO(2) liberated from unlabeled phosphatidylserine. The assay employs a gas chromatog...
These in vitro studies were conducted in an attempt to elucidate the mechanism of how cell-free supernatant fluids obtained from PHA-stimulated human lymphocytes cause destruction of cells. The undiluted supernatant fluids with high activity exerted a nonspecific cytotoxic effect on many different continuous cell lines. However, upon dilution, a wi...
The polypeptides synthesized in an E. coli cell-free system under the direction of the small RNA of the satellite tobacco necrosis virus were compared with the authentic coat protein of this virus. Many of the tryptic peptides obtained from the two types of proteins moved identically upon high-resolution cation exchange column chromatography, but d...
peer reviewed / Benzylpenicillin and cephaloridine reacted with the exocellular dd-carboxypeptidase–transpeptidase from Streptomyces R39 to form equimolar and inactive antibiotic–enzyme complexes. At saturation, the molar ratio of chromogenic cephalosporin 87-312 to enzyme was 1.3:1, but this discrepancy might be due to a lack of accuracy in the me...
Experimental data are presented on the intracellular localization in rat liver of three enzymes which are involved in the biosynthesis of phosphatidylethanolamine and diphosphatidylglycerol. These enzymes are phosphatidylserine decarboxylase, CDP-diglyceride-l-alpha-glycerophosphate phosphatidyl transferase, and phosphatidylethanolamine-l-serine ph...
An In Vitro Microassay for Lymphotoxin (LT) is described. Target cell monolayers are established in the wells of a microtiter assay plate at a density of 100-500/well. Dilutions of Lymphotoxin containing medium are placed upon the target cell monolayers. The plates are sealed with a gas impervious film, and the cells are incubated for 24-48 hr. The...
Phagocytosis of cholesterol-containing particles resulted in the formation of an intralysosomal cholesterol compartment. Cholesterol was excreted out of the macrophage with a single exponential rate which depended on the concentration of acceptor lipoproteins in the medium. Exchange kinetics performed on cells which had ingested particulate cholest...
