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91.
92.
Ji?Won?Lee Eun?Jung?Lee Seung?Sik?Yoo Sung?Hoon?Park Hee?Sook?Kim Eun?Yeol?LeeEmail author 《Biotechnology and Bioprocess Engineering》2003,8(5):306-308
Enantioselective hydrolysis for the production of chiral styrene oxide was investigated using the epoxide hydrolase activity
of a newly isolatedRhodosporidium kratochvilovae SYU-08. The effects of reaction prameters—buffer type, pH, temperature, initial substrate concentrations, phenyl-1,2-ethanediol
concentrations on hydrolysis rate, and enantioselectivity—were analyzed. Optically active (S)-styrene oxide with an enantiomeric excess higher than 99 % was obtained from its racemate with a yield of 38 % (theoretically
50% maximum yield) from an initial concentration of 80 mM. 相似文献
93.
Calcium alginate entrapment of the yeast Rhodosporidium toruloides for the kinetic resolution of 1,2-epoxyoctane 总被引:1,自引:0,他引:1
Resting cells of the yeast Rhodosporidium toruloides (UOFS Y-0471) were immobilised in calcium alginate beads for the enantioselective kinetic resolution of racemic-1,2-epoxyoctane. The initial activity exhibited by immobilised cells was almost 50% lower than that of the free counterpart but was extremely stable when compared to the free cells. The concentration of the immobilised biomass had no effect on apparent enzyme activity but did lead to a decrease in single cell activity. An increase in both the alginate and CaCl2 concentrations used for bead preparation led to a decrease in enzyme stability. An increase in the alginate concentration led to an increase in bead diameter. The stoichiometric equation for cross-linking of alginate was only obeyed when CaCl2 concentrations higher than 0.4 M were utilised for bead preparation. 相似文献
94.
A Pseudomonas sp. was isolated with enantioselective epoxide hydrolase activity to ethyl 3-phenylglycidate. Cells grown on sucrose and suspended in 10% (v/v) dimethyl formamide as co-solvent produced (2R,3S) ethyl 3-phenylglycidate with 95% ee and 26% yield in 12 h from 0.2% (w/v) of the racemate. 相似文献
95.
96.
Does enhanced expression of the Na+-CA2+ exchanger increase myocardial vulnerability to ischemia/reperfusion injury in rabbit hearts? 总被引:1,自引:0,他引:1
Matsumoto T Miura T Miki T Nishino Y Nakamura Y Shimamoto K 《Molecular and cellular biochemistry》2003,252(1-2):141-147
The present study focused on examining the efficacy of feeding a rutin-glucose derivative (G-rutin) to inhibit glycation reactions that can occur in muscle, kidney and plasma proteins of diabetic rats. Both thiobarbituric acid-reactive substance levels and protein carbonyl contents in muscle and kidney were significantly (p < 0.05) reduced in streptozotocin-induced diabetic rats fed G-rutin supplemented diet, compared to diabetic rats fed control diet. The N
-fructoselysine content in muscle and kidney, a biomarker of early glycation reaction, was markedly (p < 0.05) increased by diabetes, but significantly (p < 0.05) reduced in diabetic rats fed G-rutin. Advanced glycation end-products (AGEs) in serum and kidney protein were measured by immunoblot using anti-AGE antibody, and were also reduced in diabetic rats fed dietary G-rutin. Feeding G-rutin also slightly inhibited aldose reductase activity in these animals. These results demonstrate for the first time that dietary G-rutin consumption can provide potential health benefits that are related to the inhibition of tissue glycation reactions common to diabetes. 相似文献
97.
Carmi N Zhang G Petreikov M Gao Z Eyal Y Granot D Schaffer AA 《The Plant journal : for cell and molecular biology》2003,33(1):97-106
Raffinose and stachyose are ubiquitous galactosyl-sucrose oligosaccharides in the plant kingdom which play major roles, second only to sucrose, in photoassimilate translocation and seed carbohydrate storage. These sugars are initially metabolised by alpha-galactosidases (alpha-gal). We report the cloning and functional expression of the first genes, CmAGA1 and CmAGA2, encoding for plant alpha-gals with alkaline pH optima from melon fruit (Cucumis melo L.), a raffinose and stachyose translocating species. The alkaline alpha-gal genes show very high sequence homology with a family of undefined 'seed imbibition proteins' (SIPs) which are present in a wide range of plant families. In order to confirm the function of SIP proteins, a representative SIP gene, from tomato, was expressed and shown to have alkaline alpha-gal activity. Phylogenetic analysis based on amino acid sequences shows that the family of alkaline alpha-gals shares little homology with the known prokaryotic and eukaryotic alpha-gals of glycosyl hydrolase families 27 and 36, with the exception of two cross-family conserved sequences containing aspartates which probably function in the catalytic step. This previously uncharacterised, plant-specific alpha-gal family of glycosyl hydrolases, with optimal activity at neutral-alkaline pH likely functions in key processes of galactosyl-oligosaccharide metabolism, such as during seed germination and translocation of RFO photosynthate. 相似文献
98.
We measured the activity of several acid hydrolases of cultured oligodendrocytes prepared from adult bovine brain white matter to clarify the biochemical basis of bovine oligodendrocytes in vitro. Lysosomal enzyme activities were assayed by using 4-methylumbelliferyl glycosides as substrates. Lysosomal enzyme activities became higher at 8–11 days in vitro (DIV) than 4 DIV. The enrichment in acid hydrolase specific activities in oligodendrocytes may be associated with lysosomal origin of myelin-like membranes. 相似文献
99.
Hölzl H Kapelari B Kellermann J Seemüller E Sümegi M Udvardy A Medalia O Sperling J Müller SA Engel A Baumeister W 《The Journal of cell biology》2000,150(1):119-130
Drosophila melanogaster embryos are a source for homogeneous and stable 26S proteasomes suitable for structural studies. For biochemical characterization, purified 26S proteasomes were resolved by two-dimensional (2D) gel electrophoresis and subunits composing the regulatory complex (RC) were identified by amino acid sequencing and immunoblotting, before corresponding cDNAs were sequenced. 17 subunits from Drosophila RCs were found to have homologues in the yeast and human RCs. An additional subunit, p37A, not yet described in RCs of other organisms, is a member of the ubiquitin COOH-terminal hydrolase family (UCH). Analysis of EM images of 26S proteasomes-UCH-inhibitor complexes allowed for the first time to localize one of the RC's specific functions, deubiquitylating activity.The masses of 26S proteasomes with either one or two attached RCs were determined by scanning transmission EM (STEM), yielding a mass of 894 kD for a single RC. This value is in good agreement with the summed masses of the 18 identified RC subunits (932 kD), indicating that the number of subunits is complete. 相似文献
100.
Structure and function of S-adenosylhomocysteine hydrolase 总被引:6,自引:0,他引:6
Turner MA Yang X Yin D Kuczera K Borchardt RT Howell PL 《Cell biochemistry and biophysics》2000,33(2):101-125
In mammals, S-adenosylhomocysteine hydrolase (AdoHcyase) is the only known enzyme to catalyze the breakdown of S-adenosylhomocysteine
(AdoHcy) to homocysteine and adenosine. AdoHcy is the product of all adenosylmethionine (AdoMet)-dependent biological transmethylations.
These reactions have a wide range of products, and are common in all facets of biometabolism. As a product inhibitor, elevated
levels of AdoHcy suppress AdoMet-dependent transmethylations. Thus, AdoHcyase is a regulator of biological transmethylation
in general. The three-dimensional structure of AdoHcyase complexed with reduced nicotinamide adenine dinucleotide phosphate
(NADH) and the inhibitor (1′R, 2′S, 3′R)-9-(2′,3′-dihyroxycyclopenten-1-yl)adenine (DHCeA) was solved by a combination of
the crystallographic direct methods program, SnB, to determine the selenium atom substructure and by treating the multiwavelength anomalous diffraction data as a special
case of multiple isomorphous replacement. The enzyme architecture resembles that observed for NAD-dependent dehydrogenases,
with the catalytic domain and the cofactor binding domain each containing a modified Rossmann fold. The two domains form a
deep active site cleft containing the cofactor and bound inhibitor molecule. A comparison of the inhibitor complex of the
human enzyme and the structure of the rat enzyme, solved without inhibitor, suggests that a 17° rigid body movement of the
catalytic domain occurs upon inhibitor/substrate binding. 相似文献