Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.1 (chymotrypsin)
 10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The relationship between membrane structural properties and functions has been generally inferred from observed thermotropic phenomena. By the use of 16-dinyloxyl stearic acid spin probe we investigated the red blood cell membrane components involved in three characteristic thermotropic structural transitions occurring at 8, 20, and 40 degrees C. The transition at 8 degrees C is removed by chymotrypsin treatment at the cytoplasmic membrane layer. The 20 degrees C phase transition is unmodified after chymotrypsin treatment and occurs at 15 degrees C after complete proteolysis of intramembrane chymotrypsin-insensitive peptides. Liposomes from the total lipid extract of RBC show only one thermotropic transition at 15 degrees C. The 40 degrees C phase transition is absent in vesicles free of skeletal proteins, in vesicles obtained after RBC storage, and in low-ionic-strength resealed ghosts. Transitions at 8 degrees C and 40 degrees C appear to be due to the interactions of cytoplasmic exposed proteins with membrane, whereas the 20 degrees C transition is intrinsic to the lipid component.
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PMID:Characterization of thermotropic structural transitions of the erythrocyte membrane: a biochemical and electron-paramagnetic resonance approach. 609 Apr 82

The hypothesis of a correlation between a 10 degrees-20 degrees C lipid phase transition and the resealing process of human erythrocyte membrane has been investigated. The conditions required to reseal human erythrocyte ghosts have been studied by measuring the amount of fluorescein-labeled dextran (FD) that is trapped into the membrane. Temperature per se was sufficient to induce membrane resealing: (1) at 5 mM sodium phosphate, pH 7.8 (5P8), resealing began at 12 degrees C; (2) at salt concentrations above 8 mM sodium phosphate, it occurred at lower temperature; and (3) in isotonic saline was detected just above 5 degrees C. The removal of peripheral membrane proteins from unsealed membranes by chymotrypsin at 0 degree C in 5P8 was followed by membrane resealing. This seems to imply that the presence of proteins is necessary to maintain the membrane unsealed. Protein-induced lateral phase separation of lipids may be a reasonable mechanism for the observed phenomena. In fact, the permeability of phosphatidylserine-phosphatidylcholine mixed liposomes to FD is modified by lipid lateral phase separation induced by pH or poly-L-lysine. Electron spin resonance studies of membrane fluidity by a spin labeled stearic acid showed a fluidity break around 11 degrees C, which may be due to a gel-liquid phase transition. Fluidity changes are abolished by chymotrypsin treatment. It is suggested that a lateral phase separation is responsible for the permeability of open ghosts to FD. Accordingly, disruption of phase separation apparently produces membrane reconstitution. In this respect peripheral proteins and particularly the spectrin-actin network, may play a major role in membrane resealing.
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PMID:Protein-dependent lipid lateral phase separation as a mechanism of human erythrocyte ghost resealing. 618 Oct 83

The activity of chymase was markedly inhibited by fatty acids with carbon chain lengths of 14-22 at doses greater than 0.02 microM, irrespective of the number of double bonds. Cis acids with a carbon chain length of 18, such as stearic acid, oleic acid, linoleic acid, and linolenic acid were potent inhibitors, whereas the trans isomer of oleic acid, elaidic acid, showed less inhibitory activity. The extent of inhibition by oleyl alcohol was almost the same as that by oleic acid, suggesting that the acid moiety itself was not necessary for the inhibition; but a fatty acid with a terminal functional amide, oleamide, showed little inhibitory activity. The inhibition was noncompetitive and was reversible, and the Ki value of oleic acid was 2.7 microM. Stearic acid and oleic acid inhibited all chymotrypsin-type serine endopeptidases tested. The ID50 values of these fatty acids for atypical mast cell protease were higher than those for the other chymotrypsin-type serine endopeptidases tested. Other proteases, such as papain, trypsin, collagenase, and carboxypeptidase A, except cathespin D, were not affected by stearic or oleic acid.
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PMID:Inhibition of chymase activity by long chain fatty acids. 642 74