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Biomedical subjects

K Konopka

Publications and source records attributed to K Konopka.

At least 55 records · Page 3Linked to original sources

The effect of chloramphenicol and cycloheximide on the activity of enzyme "markers" of mitochondrial substructures of the rat liver.

Chloramphenicol and cycloheximide exert in vivo inhibitory effects on the synthesis of mitochondrial enzymes. Choloramphenicol action results in a significant decrease of the activity of enzymes being the "markers" of all submitochondrial structures including that of the outer membrane. This suggests that chloramphenicol affects biosynthesis of of "assembly protein" on mitochondrial ribosomes and thus affects incorporation of proteins, wherever they are synthesized, into the structure of the mitochondrion as a functional entity. The effect of cycloheximide depends markedly on the concentration of the inhibitor and on the time of its administration. The differences in sensitivity of examined enzymes to the drug are probably related to their differential turnover.

Animals↗

Differential effects of metal-binding agents on the D-glucose-6-phosphate phosphohydrolase activity of the rat liver.

The metal-binding agents (citrate, oxalate, bicarbonate, EDTA) exert dual effects on D-glucose-6-phosphate phosphohydrolase activity in the homogenate as well as in the subcellular fractions. The important differences of the effects are associated with the concentration of the chelator and with time of its addition. The small (appropriate) concentrations of the metal-binding agents stimulate and stabilize the enzyme activity. However, chelators used in higher concentrations exert the inhibitory influence on the activity of glucose-6-phosphatase. Stimulation of the reaction was observed only if the chelator was added before the enzyme-substrate complex formation has been started. The formation of the ternary complex: the enzyme(metal)-chelator substrate exerting a protective influence on the active centre has been suggested. The hypothesis of a similar action of the metal-binding agents and Pi on the glucose-6-phosphatase as a metaloproteid has been proposed.

Animals↗