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Biomedical subjects

P Friedrich

Publications and source records attributed to P Friedrich.

At least 109 records · Page 6Linked to original sources

Partial reversible inactivation of enzymes due to binding to the human erythrocyte membrane.

Hypotonic human erythrocyte ghosts, devoid of the original glyceraldehyde-3-phosphate dehydrogenase content of the red cell, bind added glyceraldehyde-3-phosphate dehydrogenases, isolated from human erythrocytes, rabbit and pig muscle, as well as rabbit muscle aldolase. There are only slight differences in the affinities towards the various glyceraldehyde-3-phosphate dehydrogenases. On the other hand, glyceraldehyde-3-phosphate dehydrogenases are bound much stronger than aldolase; in an equimolar mixture the former can prevent the binding of the latter, or replace previously bound aldolase at the membrane surface. Binding is always accompanied by the partial inactivation of enzymes, which can be reverted by desorption. Unwashed ghosts rich in hemoglobin seem to have a more pronounced inactivating effect on bound glyceraldehyde-3-phosphate dehydrogenase. In isotonic media ghosts, whether white or unwashed, reseal and do not interact with the enzymes.

Animals↗

Cross-linking and coupling of rabbit muscle aldolase and glyceraldehyde-3-phosphate dehydrogenase by glutaraldehyde.

The mode of cross-linking of rabbit-muscle aldolase and glyceraldehyde-3-phosphate dehydrogenase by glutaraldehyde was studied. The about 5 A long reagent can partly cross-link subunits within the tetramers, whereas it is readily able to make intermolecular cross-links producing polymeric enzyme species. Of the two enzymes, glyceraldehyde-3-phosphate dehydrogenase has a greater tendency to polymerize in the presence of glutaraldehyde. In the case of aldolase, the inter- and intramolecular cross-links between subunits can be distinguished by SDS gel-electrophoresis. The copolymerization pattern of the two enzymes indicates that, though the formation of mixed polyenzymes can be detected by affinity chromatography on human erythrocyte ghosts, under the conditions tested these proteins do not form heterologous enzyme complexes that could be trapped by glutaraldehyde.

Aldehydes↗