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191.
192.
193.
H Mansour M Brun-Pascaud M A Gougerot-Pocidalo J J Pocidalo 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1986,302(7):247-249
Inducers of cytochrome P450-linked mono-oxygenases increase the normobaric oxygen tolerance of the adult rat. Pulmonary inducers, as 3-methylcholanthrene and beta-naphthoflavone permit the rat survival and simultaneously a decrease of pulmonary edema. Phenobarbital, an hepatic inducer had lesser effects both on survival rate and on pulmonary and lympho?d oxygen toxicity. 相似文献
194.
Fructose-1-phosphate-6-sulfate was prepared by direct sulfurylation of fructose, and selective phosphorylation of the 6-sulfuryl isomer by phosphofructokinase. The ketose derivative was used as a substrate for aldolase and fructose-1,6-diphosphatase. Kinetic studies with aldolase showed that the alternative substrate binds one third as well as fructose-1,6-P2 yet 900 fold greater than fructose-1-P. The Vm was intermediate between the two ketose phosphates. From kinetic studies with skeletal muscle fructose-1,6-diphosphatase at pH 7.5 a Km of 8 μM and a Vm approximately 6% that for fructose-1,6-P2 was obtained. 相似文献
195.
Covalent modification of sheep heart phosphofructokinase with the affinity labeling reagent p-fluorosulfonyl[14C]benzoyl-5'-adenosine caused a loss of allosteric properties. This modification appears to occur at the binding site that is specific for the allosteric activators AMP, cAMP, and ADP (Mansour, T.E., and Colman, R.F. (1978) Biochem. Biophys. Res. Commun. 81, 1370-1376). In the current study, the site of modification has been demonstrated to be a lysine residue. A nonapeptide containing a covalently bound [14C]carboxybenzenesulfonyl group attached to alysine residue has been isolated following tryptic digestion. The amino acid sequence of the peptide is Asn-Phe-Ala-Thr-Lys-Met-Gly-Ala-Lys. The fifth residue in this sequence, lysine, contained the covalently bonded reagent. 相似文献
196.
197.
Cunningham D Danley DE Geoghegan KF Griffor MC Hawkins JL Subashi TA Varghese AH Ammirati MJ Culp JS Hoth LR Mansour MN McGrath KM Seddon AP Shenolikar S Stutzman-Engwall KJ Warren LC Xia D Qiu X 《Nature structural & molecular biology》2007,14(5):413-419
Proprotein convertase subtilisin kexin type 9 (PCSK9) lowers the abundance of surface low-density lipoprotein (LDL) receptor through an undefined mechanism. The structure of human PCSK9 shows the subtilisin-like catalytic site blocked by the prodomain in a noncovalent complex and inaccessible to exogenous ligands, and that the C-terminal domain has a novel fold. Biosensor studies show that PCSK9 binds the extracellular domain of LDL receptor with K(d) = 170 nM at the neutral pH of plasma, but with a K(d) as low as 1 nM at the acidic pH of endosomes. The D374Y gain-of-function mutant, associated with hypercholesterolemia and early-onset cardiovascular disease, binds the receptor 25 times more tightly than wild-type PCSK9 at neutral pH and remains exclusively in a high-affinity complex at the acidic pH. PCSK9 may diminish LDL receptors by a mechanism that requires direct binding but not necessarily receptor proteolysis. 相似文献
198.
199.
The properties and behaviour of common carp, Cyprinus carpio, eggs in water and in ovarian fluids were studied at different temperature, pH, and with divalent cation concentrations. The biochemical composition of zona radiata externa (ZRE) was analyzed qualitatively and quantitatively on amino acids, carbohydrates, uronic acid and sialic acids using chemical assays; on proteins using electrophoresis. Comparative biochemical studies were performed on the chub, Leuciscus cephalus, the vimba, Vimba vimba and the bleak, Chalcalburnus chalcoides. Eggs of common carp became sticky within seconds after mixing with water. Egg stickiness was not affected by water pH in a range of 6-9, by water temperatures between 4 and 30 degrees C, by divalent cations in concentrations < or =20 mmol/l, and by sodium chloride concentrations < or =50 mmol/l. Our investigations indicated that specific proteins of the cyprinid ovarian fluid are controlling (inhibiting) the initiation of egg stickiness: egg stickiness did not develop as long as the eggs were incubated in ovarian fluid. When however the ovarian fluid proteins were removed from the ovarian fluid by heat treatment, eggs developed stickiness within seconds, like they do in water. Biochemically, the ZRE consisted of nine types of proteins whereby four of them were glycoproteins. Glucose, fructose, galactose, and uronic acids were the major carbohydrates. Treatment of the egg membrane with invertase or amyloglucosidase did not affect the egg stickiness. Treatment with protease prevented stickiness. From these results and from additional histochemical results, we conclude that glycoproteins are likely to be the molecules responsible for stickiness. 相似文献
200.
Mansour Serghini Abdesslam Boutayeb Pierre Auger Najib Charouki Azeddine Ramzi Omar Ettahiri Maurice Tchuente 《Acta biotheoretica》2009,57(4):501-512
In this paper, we present a deterministic time discrete mathematical model based on multiregional periodic matrices to describe
the dynamics of Sardina pilchardus in the Central Atlantic area of the Moroccan coast. This model deals with two stages (immature and mature) and three spatial
zones where sardines are supposed to migrate from one zone to another. The population dynamics is described by an autonomous
recurrence equation N(t + 1) = A.N(t), where A is a positive matrix whose entries are estimated using data collected during biannual acoustic surveys carried
out from 2001 to 2003 onboard the Norwegian research vessel “Dr Fridtjof Nansen”. The dominant eigenvalue λ of A that gives
the long-term growth rate of fish population is smaller than one. This agrees with the stock decrease observed in the data
collected. We show that λ is highly sensitive to the recruitment rate and much less sensitive to the reproduction rate. These
results can clearly be used to define an efficient scenario in order to fight for instance against a stock decrease. 相似文献