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251.
252.
α-Glucosidase from Bacillus stearothermophilus was used as a catalyst for oligosaccharide synthesis by reversed hydrolysis. The yield of disaccharides and trisaccharides depended strongly on the units of enzyme activity added, and on the stability of the enzyme under reaction conditions. When glucose was the only saccharide present in the reaction mixture with α-glucosidase, isomaltose (51%), nigerose (25%), maltose (14%) and kojibiose (10%) were formed. In 50% glucose solution, disaccharide concentrations reached up to 400 mmol/l and trisaccharides were also produced. When other saccharides (mannose or xylose), in addition to glucose, were present in the reaction mixture, both homodisaccharides and heterodisaccharides were formed, their quantity being dependent on the glucose/saccharide acceptor ratios. The highest yields of oligosaccharides were observed with glucose alone, consistent with the observation that the enzyme stability was highest with glucose as the sole saccharide. 相似文献
253.
Jan Hlaváček Blanka Bennettová Richard Tykva Jiří Velek Václav Kašička Tomislav Barth 《International journal of peptide research and therapeutics》2000,7(2):85-92
Summary Mammal,125I-mammal, salmon, chicken I and II GnRHs and three fragments of mammal GnRH were synthesized and their effect on oogenesis
in the flesh flyNeobellieria (formerlySarcophaga) bullata (Diptera) was investigated. The peptides were prepared by the Merrifield solid phase synthesis on polystyrene/divinylbenzene
polymer using the Nα-Boc strategy in DMF and were purified by preparative RP-HPLC in a gradient of water-MeOH. From the peptides assayed, only
mammal GnRH and two of its carboxy-terminus truncated analogs remarkably affected the processes of egg development in ovarioles,
causing changes in the follicular epithelium, proliferation of its nuclei and cell division towards the inner part of the
egg chamber. The process led to the occurrence of multinuclear follicular epithelium which finally filled up almost the whole
egg chamber and then it degenerated. The inability of GnRH of other animal species to evoke the changes in the egg development
establishes the question of primary structures of GnRH responsible for these biological effects. The identity of sequences
of GnRHs from position 1 up to 6 (with the exception of chicken GnRH II) points to functionality of amino acids located in
positions 7 and 8 of the peptide chain. The radioactivity of the125I-labelled mammal GnRH with maintained oostatic activity and its receptor competition with the non-labelled mammal GnRH were
measured in slected insect organs and exhibited different residual values according to the organ and the time after application
of the peptide. A transfer of the radioactivity into the next (F1) generation was also observed.
Abbreviations:AAA, amino acid analysis; ACN, acetonitrile; Boc, tert-butyloxycarbonyl; BrZ, 2-bromobenzyloxycarbonyl; Bzl, benzyl; CZE,
capillary electrophoresis; DCC, N,N-dicyclohexylcarbodiimide; DCM, dichloromethane; DIEA, N-ethyl-diisopropylamine; DMAP,
4-dimethylaminopyridine; DMF, N,N-dimethylformamide; FAB MS, fast atom bombardment mass spectrometry; Fmoc, 9-fluorenylmethoxycarbonyl;
For, formyl; FSH, folicule stimulating hormone; GnRH, gonadotropin-releasing hormone; HOBt, 1-hydroxybenzotriazole; LH, luteinizing
hormone; RP HPLC, reversed phase high performance liquid chromatography; TFA, trifluoroacetic acid; Tos, 4-toluenesulfonyl.
The symbols of amino acids and peptides are in accordance with the 1983 recommendations of the IUPAC-IUB Joint Commission
on Biochemical Nomenclature (Eur. J. Biochem, 138 (1984) 9) 相似文献
254.
255.
Summary From tested yeast-like organisms, onlyGeotrichum candidum showed the same activity of glucose-6-phosphate dehydrogenase with both NAD+ and NADP+. i. e. 0.017–0.019 mol NADH/min. mg dry weight of cell free extracts. Omission of Mg++ in the reaction mixture did not influence the activity of the enzyme in the presence of NAD+. Cell free extracts ofEndomyces magnusii showed only low activity of this enzyme and the ratio of its activity in the presence of NAD+ and NADP+, respectively, varied in individual cultures.Rhodotorula glutinis showed only an NADP+-dependent activity. 相似文献
256.
Blanka Úlehlová 《Folia Geobotanica》1973,8(4):367-376
In 1963, 1964 and 1965, a comparative ecological study was made of the distribution of mineral elements in the soil and phytomass of some Stipa species, viz.Stipa capillata L., S. pulcherrima C. Koch,S. joannis ?elak.,S. dasyphylla ?erň.,and S. stenophylla ?erň. in various locations of Central Europe. In all species and sites studied, chemical analyses of the soil, fresh phytomass (shoots and roots) and dead phytomass were made, together with relevant statistical evaluation. IndividualStipa species differ according to their mineral composition. In comparison with fresh green plant material, the old dead plant material shows a marked increase in ash, calcium, and natrium content. Potassium, nitrogen, and phosphorus show a decrease in the dead plant material. The mineral composition of the roots differs considerably from that of green plant parts: the roots have much higher ash, phosphorus, calcium and natrium content, and lower organic matter, nitrogen, and potassium content. On the basis of the data collected, an attempt was made to estimate cycling of the individual mineral elements. 相似文献
257.
Slobodan Barbarié Branko Kozulié Blanka Ries Pavao Mildner 《Biochemical and biophysical research communications》1980,95(1):404-409
The protoplast-secreted acid phosphatase of yeast was purified about 60 fold by ultrafiltration, gel filtration and chromatography on DEAE-Sephadex A-25. It was established that the enzyme is free of inactive proteins as well as polysaccharides and contains 48% of neutral sugars. The failure to separate the protein from the carbohydrates by several procedures indicates that the carbohydrate part is covalently linked to the protein. A pronounced heterogeneity of the enzyme with respect to charge as well as to molecular weight was found. The data obtained by gel filtration indicated enzyme heterogeneity in respect to carbohydrate content. 相似文献
258.
259.
Blanka Rovenská 《Biologia Plantarum》1963,5(2):161-165
Sledovali jsme semeník p?enice (Triticum aestivum L. var.erythrospermum cv. Niva, jarní) od oplození vají?ka a? do plné zralosti obilky. Na trvalých preparátech jsme pozorovali tvorbu oplodí a osemení. Zjistili jsme, ?e v dospělé obilce oplodí těsně lne k osermení, z něho? z?stala zachována pouze jednolitá vrstva krytá kutikulou. Epidermis a hypodermis nesr?stá s p?í?nými buňkami, nýbr? pouze k ním p?isychá; je tě?ké mluvit o sr?stu tam, kde skon?il proces dělení a kde vrstvy pletiv jsou odděleny kutikulou. 相似文献
260.
Cloning of the glycerol kinase gene of Bacillus subtilis 总被引:1,自引:0,他引:1
A 3.5 kb fragment of Bacillus subtilis DNA which contains wild type alleles of mutations in glpK (glycerol kinase) and glpD (glycerol-3-phosphate [G3P] dehydrogenase) was cloned in plasmid pHV32 in Escherichia coli. The cloned fragment expresses glycerol kinase in B. subtilis mutants carrying the mutations glpK11 and recE4 after induction with glycerol or G3P whereas it does not express G3P dehydrogenase. The cloned fragment thus contains the complete glpK but probably only part of glpD. 相似文献