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1.
T Takabe M Nishimura T Akazawa 《Biochemical and biophysical research communications》1976,68(2):537-544
Ribulose-1,5-bisphosphate car?ylase (E.C. 4.1.1.39) from 2 blue-green algae, Plectonema boryanum and Anabaena variabilis, was isolated by sucrose density gradient centrifugation. Both enzymes had a sedimentation value of about 18s, similar to that of Chromatium enzyme. The presence of two subunits (A, B) in the algal enzyme was demonstrated by Nadodecyl sulfate polyacrylamide gel electrophoresis. The molecular weight of the two subunits was determined: for Plectonema A, 5.4 × 104 and B, 1.3 × 104 and Anabaena A, 5.2 × 104 and B, 1.3 × 104, respectively. The car?ylase reaction catalysed by the algal enzyme was similar to the higher plant enzyme in exhibiting the Mg2+-effect, the optimal pH shifting from alkaline to neutral by elevating the concentration of Mg2+ in the assay mixture. The rabbit antisera developed against the spinach ribulose-1,5-bisphosphate car?ylase and its catalytic oligomer exhibited significant inhibitory effects on the car?ylation reaction catalysed by the algal enzyme. 相似文献
2.
Ken-ichi Ishiwata Tadashi Suzuki Satoru Iwamori Setsuo Yoshino Nobuyoshi Makiguchi 《Biotechnology letters》1990,12(3):185-190
Summary The tryptophan synthase genes,trpA andtrpB, from a moderate thermophile,Bacillus
stearothermophilus IFO13737, were expressed efficiently inEscherichia
coli. The recombinant tryptophan synthase amounted to 22% of the soluble cellular protein, and was purified to homogeneity by three steps. The enzyme is more thermostable thanE.coli tryptophan synthase, especially the subunit. The enzyme is also more resistant to sodium dodecylsulfate and methanol thanE.coli enzyme. 相似文献
3.
Summary The glucose isomerase activity ofStreptomyces haeochromogenes strains 1 and 2 varies considerably with the assay conditions (pH, glucose concentration,etc.). Nine other species of streptomyces were tested under conditions optimal forS.phaeochromogenes 2. The highest enzyme activity was found inS.nigrificans 3014. 相似文献
4.
Summary Protoplast fusion was carried out between two strains ofAspergillus
niger 8-2, a fast growing culture and poor producer of glucoamylase enzyme andA.niger 8-7, a slow growing culture and good producer of the enzyme. The nonconidiating fused mass in presence of benomyl, produced fast growing segregants showing various combinations of the two parental gene markers. Some of the segregants produced up to 68% more glucoamylase than the better yielding parent 8-7. 相似文献
5.
Kyung Hoon Jung Jai Yun Lim Seung Jong Yoo Jae Heung Lee Moo Young Yoo 《Biotechnology letters》1987,9(10):703-708
Summary Conditions for the production of intracellular fructosyl transferase fromA.
pullulans were investigated. Sucrose was an excellent carbon source, and there was a tendency for the enzyme production to be increased as sucrose concentration was increased. Both 0.5% phosphate and 2% sodium nitrate had positive effects on enzyme production. It was possible to increase the intracellular enzyme production up to 140% by increasing the concentration of magnesium sulfate from 0.05 % to 0.2%. 相似文献
6.
Summary An intracellular enzyme was located inSerratia
plymuthica which produced isomaltulose from sucrose. The enzyme was purified giving a preparation with a specific activity of 1,285. It has pH and temperature optima of 6.0 and 30°C, respectively. The enzyme was stable retaining 100% activity after 2 weeks at 30°C. It had an isoelectric point at pH 9.0, a Mr of 79,500 and the Km for sucrose was 65.3mM. The enzyme converted 40% (w/v) sucrose to isomaltulose with an efficiency of 87%. 相似文献
7.
The utility of engineering enzyme activity is expanding with the development of biotechnology. Conventional methods have limited applicability as they require high-throughput screening or three-dimensional structures to direct target residues of activity control. An alternative method uses sequence evolution of natural selection. A repertoire of mutations was selected for fine-tuning enzyme activities to adapt to varying environments during the evolution. Here, we devised a strategy called sequence co-evolutionary analysis to control the efficiency of enzyme reactions (SCANEER), which scans the evolution of protein sequences and direct mutation strategy to improve enzyme activity. We hypothesized that amino acid pairs for various enzyme activity were encoded in the evolutionary history of protein sequences, whereas loss-of-function mutations were avoided since those are depleted during the evolution. SCANEER successfully predicted the enzyme activities of beta-lactamase and aminoglycoside 3′-phosphotransferase. SCANEER was further experimentally validated to control the activities of three different enzymes of great interest in chemical production: cis-aconitate decarboxylase, α-ketoglutaric semialdehyde dehydrogenase, and inositol oxygenase. Activity-enhancing mutations that improve substrate-binding affinity or turnover rate were found at sites distal from known active sites or ligand-binding pockets. We provide SCANEER to control desired enzyme activity through a user-friendly webserver. 相似文献
8.
Summary A simple aspartase assay was developed. Aspartase fromEscherichia
coli Crooks strain was adsorbed to -naphthyl cotton cloth by hydrophobic interaction. The adsorbed enzyme did not desorb in 1 M ammonium fumarate. The adsorbed enzyme exhibited the same pH vs. activity curve as free enzyme and had a half life of approx. 40 weeks. A column packed with the adsorbed aspartase showed 100% conversion of 1 M ammonium fumarate at a space velocity of approx. 2. 相似文献
9.
M. J. Lancaster R. J. Sharp J. R. Court I. D. McEntee R. G. Melton R. Sherwood 《Biotechnology letters》1989,11(10):699-704
Summary The optimum production of cloned carboxypeptidase G2 from plasmid pNM21 byEscherichia
coli was found to be strongly strain- and temperature-dependent. The superior host was strain RV308 and the preferred growth temperature 28°C. Copy number, which decreased during exponential growth of all strains examined, did not relate in these studies to the level of enzyme production: the strain with the highest enzyme yield also having the lowest overall copy number. 相似文献
10.
Matsushita Kazunobu Shinagawa Emiko Adachi Osao Ameyama Minoru 《Antonie van Leeuwenhoek》1989,56(1):63-72
Acinetobacter
calcoaceticus is known to contain soluble and membrane-bound quinoprotein D-glucose dehydrogenases while other oxidative bacteria such asPseudomonas orGluconobacter contain only membrane-bound enzyme. The two different forms were believed to be the same enzyme or interconvertible. Present results show that the two different forms of glucose dehydrogenase are distinct from each other in their enzymatic and immunological properties as well as in their molecular size.The soluble and membrane-bound glucose dehydrogenases were separated after French press-disruption by repeated ultracentrifugation, and then purified to nearly homogeneous state. The soluble enzyme was a polypeptide of 55 Kdaltons, while the membrane-bound enzyme was a polypeptide of 83 Kdaltons which is mainly monomeric in detergent solution. Both enzymes showed different enzymatic properties including substrate specificity, optimum pH, kinetics for glucose, and reactivity for ubiquinone-homologues. Furthermore, the two enzymes could be distinguished immunochemically: the membrane-bound enzyme is cross-reactive with an antibody raised against membrane-bound enzyme purified fromPseudomonas but not with antibody elicited against the soluble enzyme, while the soluble enzyme is not cross-reactive with the antibody of membrane-bound enzyme.Data also suggest that the membrane-bound enzyme functions by linking to the respiratory chain via ubiquinone though the function of the soluble enzyme remains unclear. 相似文献
11.
Summary Some nutritional factors that affect lipase yields byRhizopus
delemar were studied. Dextrin proved to be the best carbon source when used at 1% level. Yeast extract was the best nitrogen source for lipase production. The presence of a lipidic source in the growth medium, at a level not higher than 2% resulted in higher enzyme production. Tween 80 exerted a positive effect on enzyme production, used in a range that goes from 0.02% to 2.00%. 相似文献
12.
o-Succinylbenzoic acid (OSB) is an intermediate in the biosynthesis of shikimatederived anthraquinones. The cell free activation of o-succinylbenzoic acid in extracts of anthraquinone producing cells of Galium mollugo L. is demonstrated for the first time. This activation depends on the presence of ATP, coenzyme A and Mg2+. The o-succinylbenzoic acid coenzyme A ester was identified by converting it to 1,4-dihydroxy-2-naphthoic acid by a bacterial enzyme, viz. naphthoatesynthase. It is thus demonstrated that the o-succinylbenzoic acid coenzyme A ester derived from bacteria and from Galium mollugo cells are identical. 相似文献
13.
Source of pyrrole-2-carboxylate in mammalian urine 总被引:1,自引:0,他引:1
Pyrrole-2-car?ylate, earlier reported in human urine and labeled in rat urine after administration of radioactive proline, arises more directly from labeled hydroxyproline. Antibiotic treatment appeared to exclude epimerization of administered hydroxy-L-proline to a D-epimer by intestinal bacteria. A likely reaction for the in vivo conversion is hydroxy-L-proline oxidation by the L-amino acid oxidase of rat kidney, demonstrable with purified enzyme. Crystalline D-amino acid oxidase also catalyzes a slow oxidation of hydroxy-L-proline. These two reactions are adequate to account for the normal excretion of pyrrole-2-car?ylate by a number of species. 相似文献
14.
Summary A strain ofBacillus
subtilis was found to produce a cellobiase resistant to catabolic repression by glucose. When the structural gene encoding cellobiase was cloned and expressed inEscherichia
coli, the enzyme produced was resistant to repression by glucose. 相似文献
15.
Héctor S. Barra Carlos E. Argaran˜a 《Biochemical and biophysical research communications》1982,108(2):654-657
Spermine, spermidine and putrescine produce dose dependent stimulation of the invitro tubulinyl-tyrosine carboxypeptidase. Maximal stimulation was obtained with spermine, spermidine or putrescine at 0.06 mM, 1 mM and 6 mM, respectively. At higher concentrations, the enzyme activity was inhibited. The enzyme was also activated by Mg++; the concentration formaximal effect was 4–6 mM. The stimulation produced by optimal concentration of each amine was unaffected by Mg++ up to 2 mM; higher concentration of Mg++ showed inhibitory effect. At optimal Mg++ concentration, the carboxypeptidase activity was inhibited by increasing amine concentration. The amines at 0.5 or 5 mM did not produce any effect on the incorporation of tyrosine catalyzed by tubulin tyrosine ligase. 相似文献
16.
Fluoride ion is released nearly stoichiometrically when (?)-erythro-fluorocitrate is incubated with aconitase. The release of F? parallels the loss in activity and could arise from direct displacement of F? by a base on the enzyme or from dehydration to fluoro-cis-aconitate and attack of an enzymic base to release F?. Aconitase inactivated by 14C-fluorocitrate does not retain radioactivity when passed through G-50 Sephadex or precipitated by ammonium sulfate. Fullenzymicactivity can be regained after either of these treatments by activation by cysteine and ferrous salts. These data are consistent with the report of fluorocitrate being a competitive (and non-competitive) inhibitor of aconitase (Villafranca, J.J. (1972) Intra-Science Chem. Rept. 6 (4), 1–11) which rapidly inactivates the enzyme. This inactivated enzyme may be a very labile covalent complex, a very tight complex between enzyme and fluoro-cis-aconitate or a tight complex between a defluorinated deravitive of fluorocitrate.In the course of Peters (1957) extensive work on the toxic effects of fluoroacetate, he determined that fluoroacetate was metabolically converted to fluorocitrate. This finding and the fact that citrate levels rise soon after ingestion of fluoroacetate led to the suggestion that fluorocitrate inactivates aconitase (E.C. 4.2.1.2).Recently, conflicting reports concerning the site of inactivation in mitochondria by the inhibiting isomer of fluorocitrate, (?)-erythro-fluorocitrate (1R:2R, 1-fluoro-2-hydroxy-1,2,3-propanetricarboxylate) have appeared (Eanes et al. 1972; Brand et al, 1973). Eanes et al. (1972) contends that the tricarboxylate carrier is the site of inhibition, while Brand et al. (1973) has compelling evidence that aconitase is the site of inhibition. This controversy is a matter of intrepretation of the results and a greater knowledge of the inactivation of aconitase by fluorocitrate may be useful in these interpretations. The results reported herein are concerned with the mechanism of inactivation of purified mitochondrial aconitase by fluorocitrate and demonstrate that this reaction is readily reversible. 相似文献
17.
Summary The regio- and stereoselective biotransformation of bicyclo (3. 2. 0) hept-2-en-6-one by the NADH-dependent Baeyer-Villiger monooxygenase from camphorgrownPseudomonas putida NCIMB 10007 has been shown to yield a chiral lactone not accessible by curently-used biocatalysts. The biotransformation can be conductedin vitro using two alternative coupled enzyme systems (alcohol dehydrogenase and monooxygenase: formate dehydrogenase and monooxygenase) within situ recycling of NAD+/NADH. 相似文献
18.
Summary Fifteen strains of yeast, which produced an extracellular amylolytic enzymes, were isolated from nature. One of them produced more than 100 times the enzyme activity in comparison with the 14 strains and the extremely hyperproducing strain of yeast was identified asCandida
sp. 347. Paper chromatograms of the amylolytic enzyme demonstrated activity of amyloglucosidase. The optimum pH for activity of the enzyme was 5.5–6.0 and optimum temperature was 60°C. 相似文献
19.
A. P. McHale 《Biotechnology letters》1988,10(5):361-364
Summary The thermophilic fungusTalaromyces
emersonii CBS 814.70 was co-immobilized with cellulose in calcium alginate beads. Cellulose production by this system was compared with a conventional process. The immobilized system continued to produce enzyme in a batch-fed reactor system while the non-immobilized had ceased production; levels of enzyme produced by the immobilized system were almost twice the maximum produced by the non-immobilized system. 相似文献
20.
The CAT gene which codes for the enzyme chloramphenicol acetyltransferase was found to be ineffective as a reporter gene in cells and tissues of Brassica species. High levels of endogenous CAT activity were found to be widespread among this genus and did not appear to be distributed in a tissue- or cell-specific manner. Moreover, the presence of an inhibitor of CAT activity was discovered in Brassica napus and Brassica juncea. This inhibitor appeared to act selectively on bacterial CAT in transgenic plants. These findings provided an explanation for difficulties experienced in the detection of transgenic CAT activity in B. napus. 相似文献