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Biomedical subjects

F Y Yang

Publications and source records attributed to F Y Yang.

59 records · Page 4Linked to original sources
PubMed1983

Mg2+-mediated change in lipid fluidity enhances the reconstituted H+-ATPase activity.

The results by using ANS fluorescent probe and spin labels 5-NS show that the fluidity of L. (H+-ATPase) +Mg2+ (H+-ATPase from pig heart mitochondria reconstituted in the presence of Mg2+) is less than that of L. (H+-ATPase) -Mg2+ (proteoliposome reconstituted in the absence of Mg2+). But no significant difference in fluidity has been observed when both reconstituted systems were monitored by using spin labels 12-NS and 16-NS. This indicates that Mg2+ may cause changes in fluidity of the lipid molecules near the surfaces of the bilayers, but does not affect significantly the fluidity of the deeper layer of the reconstituted system. It is tentatively supposed that in the presence of Mg2+, enhancement of activities of reconstituted H+-ATPase may be due to the Mg2+-mediated change in physical state of the lipids in the more superficial region of lipid bilayers so as to ensure a suitable conformation of ATPase complex, thereby possessing higher activity.

Lipids↗
PubMed1981

Studies on incorporation of membrane protein into liposomes--effect of divalent cations on reconstitution of pig heart mitochondrial H+-ATPase into liposomes.

During the process of reconstitution of pig heart mitochondrial H+-ATPase on liposomes by cholate dialysis method, 1 mM Mg2+ in the dialysis medium can obviously increase activities of the reconstituted H+-ATPase (32Pi-ATP exchange, enzyme activity and its sensitivity to oligomycin or DCCD and ATP-dependent ANS 1) fluorescence). Besides Mg2+, effects of other divalent cations and spermidine on the H+-ATPase reconstitution have been compared. The effectiveness of the divalent cation activation of 32Pi-ATP exchange of the reconstituted H+-ATPase, decreased in the order: Mg2+ greater than Ca2+ greater than Mn2+ greater than Sr2+, while that of increasing the sensitivity to the inhibitors: Ca2+ greater than Mg2+ greater than Mn2+ greater than Sr2+. No significant effect on the H+-ATPase reconstitution has been found with Cd2+, Zn2+ and spermidine3+. Mechanism of action of the divalent cations on reconstitution has been discussed.

Adenosine Triphosphatases↗
PubMed1975

Purification and properties of the anticoagulant principle of Trimeresurus gramineus venom.

By means of DEAE-Sephadex A-50 column chromatography, Trimeresurus gramineus venom was separated into 12 fractions. Fraction 8 had marked anticoagulant action in the tests of whole blood clotting time, calcium clotting time and plasma prothrombin time. Fraction 8 was rechromatographed on Sephadex G-100, then on DEAE-Sephadex A-50 again, and finally on Sephadex G-100, and a single peak was obtained. The patterns of microzone and disc electrophoresis also showed a single band. A single symmetrical boundary with 1.70 Svedberg units was obtained by ultracentrifugation. The estimated molecular weight was 19 500. The isoelectric point was pH 4.5. Chemical analysis showed that the anticoagulant principle was a glycoprotein and that it was thermolabile. The anticoagulant activity of this purified principle was 3.5 times higher than that of the crude venom. Fraction 5 potentiated its anticoagulant activity to 10 times higher than that of the crude venom. This principle did not possess caseinolytic, tosyl-L-arginine methyl ester esterase, phospholipase A, phosphodiesterase, alkaline phosphomonoesterase, fibrinolytic, hemorrhagic or local irritating activities. The purified anticoagulant principle did not destroy fibrinogen, induce fibrinolysis, inactivate thrombin nor interfere with the interaction between thrombin and fibrinogen. However, a marked inhibition of prothrombin activation was caused by the anticoagulant principle. The inhibition of prothrombin activation was not due to the destruction of prothrombin or its activation factors, but due to an interference in the interaction between prothrombin and its activation factors because of the reversible binding of these factors with the anticoagulant principle of the venom.

Amino Acids↗