Factors controlling trypsin activated peptide kinases in healthy and diabetic men

Sasaki, H.; Sasaki, T.; Iwasaki, T.; Kobayashi, T.

Jikeikai Medical Journal 38(4): 321-337


ISSN/ISBN: 0021-6968
Accession: 007341621

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The phosphorylating activity of synthetic Ser-peptide was stimulated with a small amount of trypsin. The activity of basal and trypsin-activated peptide kinase in human lymphocytes was stimulated with phytohemagglutinin (PHA), interleukin-2 (IL-2), platelet-derived growth factor (PDGF) and insulin. Lymphocytes exhibited early increases in the phosphorylating activity with the concentrations of PHA and IL-2. The characteristics of this kinase are that the enhancement of phosphorylating activity could not be eliminated by protein kinase inhibitors, but inhibition of kinase was caused by unsaturated fatty acids. Trypsin-activated peptide kinase was activated by incubating cells with concentrations of MgCl2. No activation of kinase was found in cells incubated with insulin and PDGF. There results suggest that this kinase in involved in the early phase of intracellular mitogenic processes. There may be considerable modulation of peptide kinase in cells through a pathway mediated by unsaturated fatty acids and a possible magnesium-dependent step. Kinase activities in lymphocytes were not affected by the conditions of high levels of free fatty acid or potassium ion in sera from diabetic patients. This suggests that high levels of the factors in sera transduced no pathological changes in the function of the peptide phosphorylating processes inside the lymphocytes.