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Biomedical subjects

O Z Sellinger

Publications and source records attributed to O Z Sellinger.

At least 55 records · Page 3Linked to original sources
PubMed1976

Neuronal N-acetyl-beta-D-glucosaminidase. Evidence for its biosynthesis in vitro.

Neuronal cell bodies, isolated in bulk from 8-day-old rat cerebral cortices, were incubated in the presence of a 3H-labelled amino acid mixture, and subcellular fractions isolated by differential centrifugation. The particulate fractions were frozen/thawed in 0.20 M-sucrose/0.1 M-KCl [Selling et al. (1973) Biochim. Biophys. Acta 315, 128-146] and the profiles of acid-insoluble radioactivity and N-acetyl-beta-D-glucosaminidase (glucosaminidase) activity compared in the resulting non-sedimentable fractions by DEAE-cellulose chromatography and cellulose acetate electrophoresis. Radioactivity and glucosaminidase activity co-migrated to a significant extent. Electrophoresis revealed that after 1 min of incubation 42% of the radioactivity of the non-sedimentable microsomal fraction after freezing and thawing co-migrated with an intensely fluorescent band of glucosaminidase activity. Since the pellet fraction obtained on freezing/thawing the microsomal fraction contained up to 75% of the RNA, 95% of the radioactivity and 45% of the glucosaminidase, a detailed study of the association between its radioactivity and nascent glucosaminidase activity was undertaken. After 1 and 2 min of incubation, followed by centrifugation of the microsomal pellet on 35-60% (w/v) sucrose density gradients, radioactivity and glucosaminidase activity exhibited parallel profiles in the region of heavy polyribosomes and at the top of the gradient which contains spontaneously released nascent polypeptide chains. DEAE-cellulose chromatography of these chains revealed glucosaminidase A to be the principal nascent glucosaminidase component, with glucosaminidases B and C as minor peaks. After 2 min of incubation, all of the glucosaminidase components appeared labelled, and glucosaminidase A exhibited two distinct sub-components. The pattern of glucosaminidase labelling in the soluble and microsomal fractions suggested that newly formed glucosaminidase molecules traverse both the cellular sap and the lumen of the endoplasmic reticulum. Only glucosaminidase A reacted specifically with concanavalin A and radioactive glucosaminidase A could be successfully regenerated by treatment with alpha-methyl-D-glucoside. Glucosaminidase A and a substantial portion of the radioactivity associating with it could be readily converted into glucosaminidase B by re-chromatography on DEAE-cellulose and by reaction of the concanavalin A-glucosaminidase A complex with methyl glucosides.

Acetylglucosaminidase↗
PubMed1976

A comparison of the ATP: L-methionine-S-adenosyltransferase of rat cerebral cortex and cerebellum.

The ATP: L-methionine-S-adenosyltransferase of rat cerebral cortex and cerebellum was found to be differentially responsive to solubilization by sodium deoxycholate. Furthermore, the cerebellar enzyme was markedly less sensitive to inactivation by deoxycholate and to storage at 4 degrees C. The specific activity of the cerebellar enzyme was significantly higher and the two enzyme activities also exhibited differences in apparent Km values for L-methionine.

Animals↗
PubMed1975

Cerebellar N-acetyl-beta-D-glucosaminidase: a study of the enzyme in bulk-isolated purkinje and granule cells.

The specific activity of the lysosomal glycosidase N-acetyl-beta-D-glucosaminidase was determined in Purkinje cell bodies and granule cells isolated in bulb from cerebella of 13-, 15- and 18-day-old rats, and somewhat higher values were found for the enzyme in the Purkinje cell bodies. Although the pH profile of N-acetyl-beta-D-glucosaminidase in both neuronal types was similar, the activity in the granule cells exhibited two "pH optima". The glycosidase could be readily solubilized from both neuronal types by repeated freezing and thawing and, upon sedimentation in sucrose density gradients, the solubilized activity appeared as two distinct molecular components. The findings demonstrate the feasibility of detailed and direct comparative studies of neuron-specific patterns of enzymatic development and the excellent suitability of bulk-isolated cells for this purpose.

Age Factors↗
PubMed1973

Age-dependent utilization of phenylalanine for the synthesis of neuronal and glial proteins.

1. Groups of 5-, 10-, 18- and 43-day old rats were injected intracerebrally with a single dose of [U14C] phenylalanine and its conversion to acid-soluble metabolites was determined in the cerebral cortex over a period of 24 h. Although the most rapid utilization of [14C] phenylalanine occurred initially in the oldest group, by 45 min the 18-day old cortex had the lowest levels of unchanged [14C] phenylalanine; by 24 h [14C] phenylalanine was, in turn, lowest in the 10-day old cortex. 2. The specific radioactivity of [14C] phenylalanine decreased rapidly at all ages for the first 2 h; it then continued to decrease in the two younger age groups while it remained virtually constant in the two older ones. 3. We also determined the incorporation of [14C] phenylalanine into, and the loss of radioactivity from, cortical, glial and neuronal proteins, isolated from animals injected on their 10th, 18th and 43rd day of life and followed over a period of two weeks. a. The proteins of the 10-day old cortex attained the highest specific radioactivity and were labeled at the highest rate. b. The glial proteins and particularly those of the 10-day old cortex were consistently more highly radioactive than the neuronal proteins; the rates of radioactivity decay from neuronal and glial proteins were parallel, however. c. The decay of the radioactivity followed a similar time course at all ages and for all proteins examined, exhibiting two phases, a rapid one extending from day 1 (day 3 in the 18-day old cortex) to day 7 and a slower phase extending through the entire second week.

Aging↗