Biomedical subjects

A M Tometsko

Publications and source records attributed to A M Tometsko.

At least 37 records · Page 2Linked to original sources

PubMed1976

Preparation and characterization of calcium-binding and other hydrophobic proteins from synaptic membranes.

A number of hydrophobic proteins have been separated and purified to varying degrees from synaptic membranes derived from bovine brain. The proteins, which have been obtained using preparative acrylamide gel electrophoresis, have been analyzed for molecular weight, amino acid composition, peptide mapping, N-terminal amino acids, and for their ability to bind calcium and ATP. A number of the proteins bound calcium, the greatest binding being associated with a component having a molecular weight of 1.6 - 10(4), a binding capacity of 4 calcium/molecule, and a Km of 1.5 - 10(-5) M. An acidic tryptic peptide derived from this protein was evidently responsible for the calcium-binding. ATP binding appeared to be confined largely to the higher molecular weight proteins. From the peptide mapping there appears to be a similar acidic component in a number of the proteins exhibiting calcium-binding. ATP-binding was associated mainly with the high molecular weight proteins, particularly those which consisted of numerous basic tryptic peptides.

Adenosine Triphosphate↗

PubMed1976

Differential inactivation of the "L" and "Ly+" amino acid transport systems by a sulfhydryl reagent and a photo-affinity probe.

Using a substrate-stimulated amino acid efflux system, it has been shown that the "Ly+" and "L" amino acid transport systems of mouse embryo cells in culture are differentially inhibited by parachloromercuribenzene sulfonate (PCMB-S) and the photoaffinity probe 4-fluoro-3-nitrophenylazide (FNPA). Three types of evidence support the conclusion that these transport systems are mediated by separate carrier proteins. (1) The specificity of substrate-stimulated efflux is high for each system; (2) PCMB-S inhibits L-phenylalanine and L-leucine stimulated L-[3H]phenylalanine efflux with no effect on L-lysine stimulated L-[3H]lysine efflux, and (3) the photo-affinity probe FNPA inhibits L-lysine efflux with little effect on the L-phenylalanine-stimulated efflux.

4-Chloromercuribenzenesulfonate↗

PubMed1976

Inactivation of trypsin and chymotrypsin with a photosensitive probe.

The photosensitive inactivation of trypsin and chymotrypsin by 4-fluoro-3-nitrophenyl azide (FNPA) is described. A dark inhibition was observed at elevated probe concentrations, and was reversible. The enzymes were stable to photolysis in the absence of probe. Photolytic inactivation of trypsin and chymotrypsin with FNPA was found to be irreversible, and occurs in minutes at concentrations of FNPA where dark inhibition is negligible. The photoprobe was equally effective at pH 3 or pH 8. Nonspecific inactivation appears to be low, as evidenced by the stability of glucose oxidase and peroxidase to photolysis with FNPA.

Azides↗

PubMed1976