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Biomedical subjects

L Engström

Publications and source records attributed to L Engström.

At least 55 records · Page 3Linked to original sources
PubMed1987

The quantity of protein-bound [32P]phosphotyrosine in hepatocytes and fibroblasts. The effects of tyrosine protein kinase activating agents.

Tyrosine protein kinase activities have been demonstrated in transformed and normal cell systems. So far, few data on the quantity of protein-bound phosphotyrosine in intact cells have been published. A knowledge of the stoichiometric increase in phosphotyrosine in cells after hormonal induction could be of interest when evaluating the importance of the tyrosine protein kinase activities found. By the addition of a known amount of unlabeled phosphotyrosine to the precipitated protein of 32P-phosphate-labeled cells it was possible after alkaline hydrolysis to spectrophotometrically follow the phosphotyrosine during consecutive chromatographies of the material. From the specific radioactivity of the purified phosphotyrosine the initial concentration of [32P]phosphotyrosine could be calculated. The method proved to be useful for the determination of [32P]phosphotyrosine is small amounts of cells. The minimum detectable amount of [32P]phosphotyrosine was about 1 pmol, and as an example, only 2.5 X 10(6) fibroblasts were needed. By this method it was shown that platelet-derived growth factor increased protein-bound [32P]phosphotyrosine from 600 to 3,200 pmol/g of fibroblasts, while insulin only increased the [32P]phosphotyrosine from 110 to 120 pmol/g of hepatocytes.

Cells, Cultured↗
PubMed1986

Aspects on the phosphorylation of muscle phosphofructokinase by protein kinase C--inhibition by phosphofructokinase stabilisers.

Our report presents data on the phosphorylation of muscle phosphofructokinase by Ca2+-activated, phospholipid-dependent protein kinase. We have found a stoichiometrical phosphorylation (about 1.5 mol per mol subunit), and a low apparent Km (about 0.7 microM). These data speak in favor of a physiological role for the reaction, as does the fact that phosphofructokinase from a new species (rat) was successfully phosphorylated. On the other hand we present the hitherto unpublished circumstance that the phosphorylation is inhibited by conditions that stabilise the activity of phosphofructokinase. This fact makes us question the true significance of this reaction.

Adenosine Monophosphate↗
PubMed1985

Phosphorylation in vitro of fibrinogen from three mammalian species with four different protein kinases.

Human, dog, and rabbit fibrinogen served as substrates for calcium-activated, phospholipid-dependent protein kinase, cAMP-dependent protein kinase, casein kinase TS, and casein kinase S. The chains of phosphorylated fibrinogen were separated by polyacrylamide gel electrophoresis and the phosphorylation patterns, obtained on autoradiography of the gels, were found to be characteristic for each of the four protein kinases. Dog, and even more so rabbit, fibrinogen was phosphorylated more rapidly than human fibrinogen by calcium-activated, phospholipid-dependent protein kinase and by casein kinase TS. Dog fibrinogen was not a good substrate for cAMP-dependent protein kinase. The rate of phosphorylation with casein kinase S did not differ very much between the fibrinogens of the three species. In most cases the A alpha-chain was most rapidly phosphorylated. However, in dog fibrinogen incubated with casein kinase TS the B beta-chain was most rapidly phosphorylated. A substantial part of this phosphate seemed to be incorporated as phosphorylthreonine into fibrinopeptide B. In human fibrinogen incubated with the casein kinase TS preparation the gamma-chain as well as the A alpha-chain appeared to be phosphorylated.

Animals↗
PubMed1985

Appendicectomy: assessment of stump invagination versus simple ligation: a prospective, randomized trial.

The appendix stump was ligated and doubly invaginated in 374 patients and was simply ligated in 361 in a prospective, randomized trial of 735 consecutive appendicectomies. The two groups were similar with respect to sex, age, degree of appendiceal inflammation and antibiotic treatment. The incidence of wound infection and postoperative pyrexia and the postoperative hospital stay showed no significant intergroup difference. The median operating time was slightly shorter in the group without invagination. Simple ligation facilitates and shortens appendicectomy. It produces no deformation of the caecal wall that subsequently may be mistaken for a caecal neoplasm. Simple ligation is therefore recommended as standard procedure in appendicectomy.

Appendectomy↗
PubMed1984

Phosphorylation of human fibrinogen in vitro by calcium-activated phospholipid-dependent protein kinase from pig spleen.

Human plasma fibrinogen rapidly incorporated stoichiometric amounts of [32P]-phosphate when incubated with [32P]ATP and calcium-activated, phospholipid-dependent protein kinase purified from pig spleen. Half-maximal fibrinogen kinase activity was attained at less than 0.1 mM calcium acetate. The optimum concentration of phosphatidylserine was about 50 micrograms per ml. Diolein slightly potentiated the stimulatory effect of phosphatidylserine. The alpha-chain of fibrinogen, which is reported to contain endogenous phosphate (Blombäck, B., Blombäck, M., Edman, P., & Hessel, B. (1962) Nature 193, 883-884 and Doolittle, R.F., Watt, K.W.K., Cottrell, B.A., Strong, D.D., & Riley, M. (1979) Nature 280, 464-468) was phosphorylated by the protein kinase. The apparent Km value for the phosphorylation reaction (0.3-0.6 microM fibrinogen) was comparable with the Km values reported for the hitherto most effective substrate proteins for protein kinase C. Up to 5 mol phosphate per mol fibrinogen could be incorporated, indicating at least three phosphorylatable sites per half molecule.

Alkadienes↗
PubMed1982

Effect of chemical modification of a histidine and a lysine residue of pea seed nucleoside diphosphate kinase.

Chemical modification of a histidine and lysine residue inactivates pea seed nucleoside diphosphate kinase (NDP kinase). Thus there seems to be a reactive lysine residue, at the active site of pea seed NDP kinase, in addition to the histidine residue phosphorylated by the substrate ATP as a consequence of the enzyme reaction. The presence of a reactive lysine at the active site of the enzyme could explain why a small amount of N-epsilon-phospholysine, as well as 1-phosphohistidine and 3-phosphohistidine, is formed on alkaline hydrolysis of the enzyme.

Fabaceae↗