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Biomedical subjects

L Goldstein

Publications and source records attributed to L Goldstein.

At least 235 records · Page 13Linked to original sources
PubMed1975

Glutamine transport by mitochondria isolated from normal and acidotic rats.

The transport of L-glutamine by isolated rat renal mitochondria was studied by means of a rapid-filtration (Millipore Filter Corp.) technique. The movement of glutamine from the incubation medium into the inner mitochondrial compartment (matrix) was inhibited by structural analogues (6-diazo-5-oxo-L-norleucine and glutamic acid), sulghydryl-binding agents (p-chloromercuri-benzoate and mersalyl), and inhibitors of mitochondrial oxidative metabolism (azide, antimycin A, and uncouplers of oxidative phosphorylation). These results suggest that glutamine is transported across the inner membrane of renal mitochondria by a carrier-mediated system that is linked to the processes of oxidative metabolism. The transport of glutamine by isolated renal mitochondria was increased two- to threefold by chronic (5-7 days) metabolic acidosis. However, short-term metabolic acidosis did not increase the glutamine transport capacity of isolated mitochondria. A hypothesis is presented for the regulation of mitochondrial glutamine transport, in vivo, during short-term and chronic acidosis.

Acidosis↗
PubMed1975

Renal glutaminase in postnatal and adult rats.

Properties of renal phosphate-dependent glutaminase (EC 3.5.1.2), assayed in tissue homogenates, were compared in adult, 2-week-old, and newborn rats. Vmax, Km glutamine, pH optimum, inhibition by glutamate, activation by phosphate, intracellular distribution, and the possible presence of activators or inhibitors were examined. Although Vmax increased threefold during postnatal development, no major differences in the properties of the enzyme at the three stages of development were noted. It was concluded that the enzyme protein remains the same throughout development, both in biochemical properties and intracellular location, but that more of it is accumulated or is converted to an active state as the kidney matures.

Aging↗
PubMed1974

Chemically modified nylons as supports for enzyme immobilization. Polyisonitrile-nylon.

Four-component condensations between amine, carboxyl, isocyanide and aldehyde lead to the formation of N-substituted amides (Ugi, 1962). The present paper describes the use of such condensations for the introduction of chemically reactive groups on to the polyamide backbone of nylon. Polyisonitrile-nylon was synthesized by partial hydrolysis of nylon-6 powder, followed by resealing of the newly formed -CO(2)... NH(2) (-) pairs via a four-component condensation, by using acetaldehyde and 1,6-di-isocyanohexane. Polyisonitrile-nylon could also be converted into a diazotizable arylamino derivative, polyaminoaryl-nylon, by a four-component condensation by using a bifunctional amine, pp'-diaminodiphenylmethane, in the presence of an aldehyde and a carboxylate compound. The versatility of four-component condensations involving the isocyanide functional group of polyisonitrile-nylon allowed coupling of proteins, in an aqueous medium at neutral pH, through either their amino or carboxyl groups. Trypsin and papain were bound to polyisonitrile-nylon through their amino groups by a four-component condensation by using acetaldehyde and acetate; conversely, succinyl-(3-carboxypropionyl-)trypsin, pepsin and papain were coupled through their carboxyl groups in the presence of acetaldehyde and an amine (Tris). Diazotized polyaminoaryl-nylon could be utilized for the immobilization of papain, via the tyrosine residues of the enzyme.

Chemical Phenomena↗