Fermentative production of dextran using Leuconostoc spp. isolated from fermented food products

Leuconostoc spp. （LSland LI1） isolated from sauerkraut and idli batter was selected for dextran production. To enhance the yield of dextran, effects of various parameters such as sucrose concentration, pH, temperature, incubation and inoculum percentage were analyzed. The optimum sucrose concentration for the Leuconostoc spp. （LS1 and LI1） was found to be 15% and 25% respectively. Isolates produced maximum dextran after 20 h of incubation at 29℃ and the optimum pH was found between 8 and 8.5. The inoculum concentration of 7.5% was more favorable for the production of dextran by Leuconostoc spp. （LS1 and LI1）. The growth kinetic parameters were studied and compared for the strains LS1 and LI1. Mass production of dextran was carried out using a stirred tank batch reactor. FTIR analysis was done to determine the functional groups of dextran, sephadex is prepared by cross linking dextran using epichlorohydrin and the functional groups are determined by FTIR analysis.     

Immobilized copper-ion affinity adsorbent based on a cross-linked β-cyclodextrin polymer for adsorption of Candida rugosa lipase

Lipase from Candida rugosa was immobilized on a β-cyclodextrin-based polymer by adsorption and subsequent cross-linking with epichlorohydrin (EP-CD). The ligand iminodiacetic acid (IDA) was then bonded with the cross-linked β-cyclodextrin (EP-CD-IDA). This affinity adsorbent was further chelated with Cu^{2 +} for the purpose of binding affinity and stability. The properties of the immobilized lipase were assayed and compared with those of the free enzyme. Results showed that 266 µg protein with an activity of 17.85 U was bound per gram of matrix, giving 188% of the specific activity of the free enzyme and a total recovered activity of 79.7% under the optimum conditions. The pH and thermal stabilities of lipase were improved after immobilization on the β-cyclodextrin-based polymer (EP-CD-IDA-Cu^{2 +}). In addition, experimental results indicated that the residual activity of the immobilized lipase was 50% after eight cycles of reuse.     

Synthesis and Structure of Three Isomers of 1,3,4,5-Tetrachlorocyclohexene

By controlled reduction of 1,3,4,5,6-pentachlorocyclohexene isomers with lithium aluminum hydride, three isomers of 1,3,4,5-tetrachlorocyclohexene were prepared. Their structures were (34/5)-, (3/45)- and (35/4)- by PMR analyses.     

Bevantolol hydrochloride (nc-1400): Absolute configuration and direct separation of the enantiomers

Synthesis of (?)-bevantolol hydrochloride from 3,4-dimethoxyphenethylamine and (S)-(+)-m-tolyl glycidyl ether derived from (R)-(?)-epichlorohydrin established the absolute configuration of the (+) and (?) enantiomer as R and S, respectively. The purity of the enantiomers was determines using a chiral cellulose column (CHIRALCEL OD®) which allowed direct separation of the enantiomers. A separation factor (α) of 4.20 and a resolution factor (Rs) of 9.21 were obtained. © 1995 Wiley-Liss, Inc.     

The effects of busulphan on the chromosomes of normal human lymphocytes

In vitro exposure of human lymphocytes to busulphan (BUS) produced an increase in chromosome aberrations and in sister-chromatid exchange (SCE) frequency. The distribution of chromosome breaks throughout the karyotype was non-random and they occurred mainly in the G-negative bands. Certain bands had a marked susceptibility to BUS and comparisons with the human chromosome-break distributions reported for a number of drugs revealed that some of these bands were equally susceptible to other alkylating agents. Both the number of chromosome gaps and breaks and the SCE frequency increased with BUS concentration, but only the SCE dose-response was a clearly defined linear relationship. Therefore a standard SCE dose-response curve was constructed for future comparison with the results of similar investigations of patients on BUS therapy.     

Regulation of n-acetylglucosamine uptake in yeast

Various yeasts have been investigated for their ability to grow on N-acetylglucosamine as the sole carbon source and only those which are associated with the disease, candidiasis, gave positive results. The yeasts unable to grow on N-acetylglucosamine lacked the capacity to transport the aminosugar across the cell membrane. In pathogenic yeasts, two systems of different affinity for substrate were found to operate in the uptake of N-acetylglucosamine. In glucose-grown cells a constitutive, low affinity uptake system was present, but upon addition of inducer, a specific high affinity uptake system was synthesized. Experiments with the inhibitors of macromolecule synthesis suggested that the synthesis of RNA and protein is necessary for induction whereas the synthesis of DNA is not.In glucose-grown Candida albicans cells which are devoid of N-acetylglucosamine enters into the cells as phosphorylated form using a constitutive uptake system. Uranyl acetate (0.01 mM) which binds to cell membrane-associated polyphosphates, inhibited completely the inducible uptake of N-acetylglucosamine. Labelling experiments, designed to determine the temporal sequence of appearance of N-acetylglucosamine in intracellular free sugar and sugar-phosphate pools, indicated that N-acetylglucosamine first appeared in the cells as phosphorylated form. Similar results were obtained with Saccharomyces cerevisiae 3059 and some other yeasts which are devoid of N-acetylglucosamine kinase in both uninduced and induced conditions. These results are consistent with the model of van Steveninck that involves phosphorylation during transport. Furthermore, inhibitors of energy metabolism (arsenate, azide and cyanide), proton conductor (m-chlorocarbonylcyanide phenylhydrazine) and dibenzyl diammonium ion (membrane permeable cation) inhibited the inducible N-acetylglucosamine uptake in C. albicans.     

Ring-Opening of 3-β-D-Ribofuranosyl-3,7,8,9-Tetrahydropyrimido [1,2-i]Purin-8-ol and Preparation of 2-Thio- and 2-aza-Adenosine Derivatives

The adduct 3-β-D-ribofuranosyl-3,7,8,9-tetrahydropyrimido[1,2-i]purin-8-ol (2), obtained from adenosine and epichlorohydrin, underwent ring fission at basic conditions. The initial ring-opening took place at C2 of the pyrimidine unit resulting in 2-(5-amino-1-β-D-ribofuranosyl-imidazol-4-yl)-1,4,5,6-tetrahydropyrimidin-5-ol (3). Also the tetrahydropyrimidine ring of 3 could be opened resulting in 5-amino-1-(β-D-ribofuranosyl)-imidazole-4-(N-3-amino-2-hydroxyl-propyl)-carboxamide (4). In hot acid conditions, 2 was both deglycosylated and ring-opened yielding 2-(5-amino-imidazol-4-yl)-1,4,5,6-tetrahydropyrimidin-5-ol (7) as the final product. When reacting 3 with CS₂ or HNO₂ ring-closure took place and 3-β-D-ribofuranosyl-3,4,7,8,9-pentahydropyrimido[1,2-i]purin-8-ol-5-thione (5), and 3-β-D-ribofuranosyl-imidazo[4,5-e]-3,7,8,9-tetrahydropyrimido[1,2-c][1,2,3]triazine-8-ol (6), respectively, were obtained. Also, the pyrimidine ring of the epichlorohydrin adduct with adenine, 10-imino-5,6-dihydro-4H,10H-pyrimido[1,2,3-cd]purin-5-ol (10), underwent ring fission and the product was identified as 3-hydroxy-1,2,3,4-tetrahydroimidazo[1,5-a]pyrimidine-8-carboximidamide (11).     

Biocatalytic preparation of chiral epichlorohydrins using recombinant<Emphasis Type="Italic">Pichia pastoris</Emphasis> expressing epoxide hydrolase of<Emphasis Type="Italic">Rhodotorula glutinis</Emphasis>

The use of enantioselective hydrolysis for preparing chiral epichlorohydrins was investigated using recombinantPichia pastoris with the enantioselective epoxide hydrolase ofRhodotorula glutinis. The rate of the recombinant epoxide hydrolase-catalyzed enantioselective hydrolysis of racemic epichlorohydrins was enhanced by the addition of 5% (v/v) Tween 20. Enantiopure (R)-epichlorohydrins with an enantiopurity of 100%ee and a yield of 26% were obtained within 5 min from 50 mM racemates.     

头孢唑啉为配基亲和层析纯化尿激酶

利用头孢类抗生素头孢唑啉为配基,Ｓｅｐｈａｒｏｓｅ ４Ｂ为载体,用环氧氯丙烷活化法制得头孢唑啉－Ｓｅｐｈａｒｏｓｅ ４Ｂ亲和载体,配基密度为４３μｍｏｌ／ｇ湿胶。吸附尿激酶的最佳条件为ｐＨ６．０和１．０ｍｏｌ／Ｌ ＮａＣｌ;最大吸附量为１１００００ｕ／ｇ湿胶,洗脱条件为含０．５ｍｏｌ／Ｌ ＮａＣｌ,ｐＨ９．０,０．１ｍｏｌ／Ｌ甘氨酸缓冲液。将比活为５００ｕ／ｍｇ的尿激酶粗品进行层析,得到比活为４９     

Urinary excretion products of formaldehyde in the rat

Thymidine was reacted in methanol with four epoxides of varying mutagenicities: propylene oxide, glycidol, epichlorohydrin and trichloropropylene oxide. A single product was detected with each epoxide, and these products had the same retention times on silica high pressure liquid chromatography (HPLC). UV spectra of the products identified them as 3-alkylthymidines, and this was confirmed by infrared (IR) and nuclear magnetic resonance (NMR) spectra. Mass spectra (MS) analysis showed the products to be consistent with attachment at the least substituted carbon of the epoxide. Formation of 3-alkylthymidines correlated to Taft σ¹ electron withdrawing values for the substituents on the epoxides and mutagenicities in strain TA100 of the Ames Assay.