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61.
Z. Huňková V. Křen M. Ščigelová L. Weignerová O. Scheel J. Thiem 《Biotechnology letters》1996,18(6):725-730
Summary Extracellular -N-acetylhexosaminidase in basic specific activity 1.5 U/mg protein was induced 15 – 35 times (up to 50 U/mg protein) by mixture of chitooligomers (crude chitin hydrolysate), 10 – 20 times (20 – 30 U/mg protein) by N-acetylglucosamine, and 10 times (14 U/mg protein) by chitosan in Aspergillus oryzae. Addition of NaCl (15 – 23 g/l) to the cultivation medium enhanced the induction in 10 – 20 %. 相似文献
62.
Nimtz M Grabenhorst E Gambert U Costa J Wray V Morr M Thiem J Conradt HS 《Glycoconjugate journal》1998,15(9):873-883
Transgalactosylation of chitobiose and chitotriose employing -galactosidase from bovine testes yielded mixtures with 1-3 linked galactose (type I) and 1-4 linked galactose (type II) in a final ratio of 1:1 for the tri- and 1:1.4 for the tetrasaccharide. After 24 h incubations of the two purified oligosaccharide mixtures with large amounts (20-fold increase compared with standard conditions) of human 1, 3/4-fucosyltransferase III (FucT III), the type I tri-/tetrasaccharides were completely converted to the Lewisa structure, whereas approximately 10% fucosylation of the type II isomers to the Lewisx oligosaccharides was observed in long-term incubations.Employing large amounts of human 1, 3-fucosyltransferase VI (FucT VI), the type I trisaccharide substrate was exclusively fucosylated at the proximal O-4 substituted N-acetylglucosamine (GlcNAc) (20%) whereas almost all of the type II isomers was converted to the corresponding Lewisx product. 45% of the type I tetrasaccharide was fucosylated at the second GlcNAc solely by FucT VI. The type II isomer was almost completely 1-3 fucosylated to yield the Lewisx derivative with traces of a structure that contained an additional fucose at the reducing GlcNAc. The results obtained in the present study employing high amounts of enzyme confirmed our previous results that FucT III acts preponderantly as a 1-4 fucosyltransferase onto GlcNAc in vitro. Human FucT VI attaches fucose exclusively in an 1-3 linkage to 4-substituted GlcNAc in vitro and does not modify any 3-substituted GlcNAc to yield Lewisa oligosaccharides. With 8-methoxycarbonyloctyl glycoside acceptors used under standard conditions, FucT III acts exclusively on the type I and FucT VI only on the type II derivative. With lacto-N-tetraose, lacto-N-fucopentraose I, or LS-tetrasaccharide as substrates, FucT III modified the 3-substituted GlcNAc and the reducing glucose; FucT VI recognized only lacto-N-neotetraose as a substrate. 相似文献
63.
The chemical synthesis of adenosine(5') [alpha-thio]diphospho(5')ribofuranosyl-nicotinamide (NAD[S]) is described. The product occurs as a pair of diastereomers with different configuration at the sulfur-bearing phosphorus atom. The diastereomers were separated by high-performance liquid chromatography and their absolute configuration was determined after chemical degradation to the ADP[alpha S] diastereomers and chromatographic comparison with enzymically synthesized ADP[alpha S] diastereomers of known absolute configuration. Additional support for this assignment is based on different rates in the phosphodiesterase-catalyzed hydrolysis. Furthermore the synthesis of [14C]NAD[S] is described. The coenzyme activity of NAD[S] in the reaction with alcohol dehydrogenase from baker's yeast and lactate dehydrogenase from pig heart is very similar to that of beta-NAD. Also, NAD and NAD[S] serve equally well as substrates for NAD glycohydrolase from calf spleen. In contrast, no reaction was detected with NAD pyrophosphorylase, and hydrolysis of the separated NAD[S] diastereomers with snake venom phosphodiesterase showed a 26-fold and a 33-fold slower reaction rate than that of NAD. Nucleotide pyrophosphatase was less sensitive to the S substitution, hydrolyzing NAD[S] 14-times slower than NAD. Poly(ADP-ribose) polymerase from Ehrlich ascites tumor cell nuclei accepted NAD[S] as a substrate but the reaction was significantly slower and approached saturation at much lower values than with NAD. Alkaline hydrolysis of the products insoluble in trichloroacetic acid yielded AMP[S] as the main derivative. It is concluded that with NAD[S] as a substrate the nuclear acceptors were nearly exclusively mono(ADP-ribosyl) ated . 相似文献
64.
One‐year outcomes of an intense workplace cardio‐metabolic risk reduction program among high‐risk employees: The My Unlimited Potential
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Henry Guzman Sankalp Das Doris Brown Chukwuemeka U. Osondu Erica Spatz Brandon Shaffer Joann Santiago‐Charles Teresa Ochoa Joseph Mora Cynthia Gilliam Virginia Lehn Shoshana Sherriff Thinh H. Tran Janisse Post Emir Veledar Theodore Feldman Arthur S. Agatston Khurram Nasir 《Obesity (Silver Spring, Md.)》2016,24(1):71-78
65.
66.
UDP-GalNAc analogues with slight modifications in the 2-acetamido group of the GalNAc moiety are prepared in order to study their role in the mechanism of the N-acetylgalactosaminyl transferase mediated glycosylation step. The analogues with N-propionyl-, N-butyryl- and N-bromoacetyl-groups were synthesized, utilizing Khorana's morpholidate coupling method starting from D-galactosaminyl-1-phosphate after selective N-acylation of its amino group with the appropriate N-acyloxysuccinimides. Furthermore, in addition to UDP-galactosamine its 2-azido analogue has been efficiently prepared involving a metal catalyzed diazo transfer reaction. 相似文献
67.
68.
Barbara Thiem Małgorzata Kikowska Aldona Krawczyk Barbara Więckowska Elwira Sliwinska 《Plant Cell, Tissue and Organ Culture》2013,114(2):197-206
A protocol for in vitro production of genetically uniform populations of the medicinal plant Eryngium planum, rich in selected phenolic acids, has been established. Shoot-tips were collected from axenic seedlings and grown on a Murashige and Skoog basal medium supplemented with 6-Benzyladenine (BA) and Indole-3-acetic acid (IAA). The highest shoot proliferation efficiency (17 shoots per explant) was obtained when 1.0 mg L?1 BA and 0.1 mg L?1 were added. Proliferating shoots were rooted and transferred to soil (89 % frequency of survival). Flow cytometric analysis of intact (field-grown) and microrpropagated plants revealed that all plants were uniform in genome size and had similar DNA contents. Thin-layer chromatography (TLC) analysis indicated that multiple shoots and roots from in vitro-derived plants produced high amounts of phenolic acids, primarily of rosmarinic acid (RA). Levels of phenolic acids in in vitro-derived plants were similar to those of intact plants. Furthermore, high-performance liquid chromatography revealed that root cultures in liquid medium accumulated substantial levels of RA. Thus, rapid establishment of in vitro-grown organ cultures of E. planum can also serve as reliable sources for bioactive compounds. 相似文献
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70.
Ehimen C. Aneni Lara L. Roberson Wasim Maziak Arthur S. Agatston Theodore Feldman Maribeth Rouseff Thinh H. Tran Roger S. Blumenthal Michael J. Blaha Ron Blankstein Mouaz H. Al-Mallah Matthew J. Budoff Khurram Nasir 《PloS one》2014,9(1)