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81.
82.
Kenzo Yokozeki Shigeru Yamanaka Koichi Takinami Yoshio Hirose Atsuo Tanaka Kenji Sonomoto Saburo Fukui 《Applied microbiology and biotechnology》1982,14(1):1-5
Summary Lipase from Rhizopus delemar was immobilized by entrapment with photo-crosslinkable resin prepolymers or urethane prepolymers or by binding to various types of porous silica beads. The immobilized lipase preparations thus obtained were examined for their activity in converting olive oil to an interesterified fat (cacao butter-like fat), whose oleic acid moieties at 1- and 3-positions were replaced with stearic acid moieties, in the reaction solvent n-hexane. Although all of the immobilized preparations exhibited some activity, lipase adsorbed on Celite and then entrapped with a hydrophobic photo-crosslinkable resin prepolymer showed the highest activity, about 75% of that of lipase simply adsorbed onto Celite. Entrapment markedly enhanced the operational stability of lipase.Dedicated to Professor H. Holzer, Freiburg University, on his 60th birthday (June 13, 1981) 相似文献
83.
Post-embryonic development of circadian rhythm in the cricket,Gryllus bimaculatus: A rhythm reversal
Kenji Tomioka Yoshihiko Chiba 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1982,147(3):299-304
Summary Locomotor activity of the male cricketGryllus bimaculatus DeGeer was recorded from the 7th or last (8th) instar nymph. The nymph showed a diurnal rhythm (nymphal rhythm = NR), while the adult, on the contrary, was nocturnal (adult rhythm = AR) (Fig. 1). This rhythm reversal occurred suddenly 3 to 5 days after the imaginal molt, almost simultaneously with the first spermatophore formation and the start of stridulation (calling song) (Fig. 2). In addition to the antiphase relationship, both rhythms also differed in the freerunning period (tau) and wave form. Tauscdd was significantly longer in NR (24.33 h) than in AR (23.91 h) (Fig. 3). AR was characterized by a sharp activity peak in each cycle, which NR, however, lacked (Fig. 1, 3, 6). On the basis of these differences, two possibilities are discussed; one is that NR and AR are separate oscillations and the other is that both are coupled to different phase points of one oscillation.Abbreviations
LD
light dark
-
DD
constant darkness
-
LL
constant light
-
NR
nymphal rhythm
-
AR
adult rhythm 相似文献
84.
Preparation of Uridine Diphosphate-N-Acetylgalactosamine from Uridine Diphosphate-N-Acetylglucosamine by Using Microbial Enzymes 下载免费PDF全文
A method was developed for the large scale preparation of uridine diphosphate-N-acetylgalactosamine (UDP-GalNAc) from uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) by means of microbial enzymes. With Bacillus subtilis cell-free extract as a source of UDP-GlcNAc 4-epimerase, about 35% of the UDP-GlcNAc added was converted to UDP-GalNAc. After the residual UDP-GlcNAc was degraded to uridine triphosphate and N-acetylglucosamine-1-phosphate with a protamine-treated extract of bakers' yeast as a source of UDP-GlcNAc pyrophosphorylase, UDP-GalNAc was separated by anion-exchange column chromatography. The nucleotide was recovered by adsorption on charcoal and elution with ammoniacal ethanol. The final yield was about 100 μmol. 相似文献
85.
Kenji Fukuzawa Hisako Chida Akira Tokumura Hiroaki Tsukatani 《Archives of biochemistry and biophysics》1981,206(1):173-180
The antioxidative effect of α-tocopherol incorporated into lecithin liposomes was studied. Lipid peroxidation of liposome membranes, assayed as malondialdehyde production, was catalyzed by ascorbic acid and Fe2+. The peroxidation reaction, which did not involve the formation of singlet oxygen, superoxide, hydrogen peroxide, or a hydroxyl radical, was inhibited by α-tocopherol and a model compound of α-tocopherol, 2,2,5,7,8-pentamethyl-6-hydroxy-chroman (TMC), but not by phytol, α-tocopherylquinone, or α-tocopheryl acetate. One mole of α-tocopherol completely prevented peroxidation of about 100 moles of polyunsaturated fatty acid. Decrease in membrane fluidity by lipid peroxidation, estimated as increase of fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) embedded in the membrane, was also inhibited by α-tocopherol and TMC, reflecting their antioxidant functions. Cholesterol did not act as an antioxidant, even when incorporated in large amount into the liposome membranes, but it increased the antioxidative efficiency of α-tocopherol. When a mixture of liposomes with and without α-tocopherol was incubated with Fe2+ and ascorbic acid, α-tocopherol did not protect the liposomes not containing α-tocopherol from peroxidation. However, preincubation of the mixture, or addition of Triton X-100 allowed the α-tocopherol to prevent peroxidation of the liposomes not containing α-tocopherol. In contrast, in similar experiments, liposomes containing TMC prevented peroxidation of those without TMC without preincubation. Tocopherol in an amount so small as to exhibit only a slight antioxidative effect was oxidized when incorporated in egg lecithin liposomes, but it mostly remained unoxidized when incorporated in dipalmitoyllecithin liposomes, indicating that oxygen activated by ascorbic acid-Fe2+ does not oxidize α-tocopherol directly. Thus, decomposition of α-tocopherol may be caused by its interaction with peroxy and/or alkoxyl radicals generated in the process of lipid peroxidation catalyzed by Fe2+ and ascorbic acid. 相似文献
86.
Electron transfer between horse heart and Candida krusei cytochromes c in the free and phosvitin-bound states was examined by difference spectrum and stopped-flow methods. The difference spectra in the wavelength range of 540–560 nm demonstrated that electrons are exchangeable between the cytochromes c of the two species. The equilibrium constants of the electron transfer reaction for the free and phosvitin-bound forms, estimated from these difference spectra, were close to unity at 20°C in 20 mM Tris-HCl buffer (pH 7.4). The electron transfer rate for free cytochrome c was (2–3) · 104 M?1 · s?1 under the same conditions. The transfer rate for the bound form increased with increase in the binding ratio at ratios below half the maximum, and was almost constant at higher ratios up to the maximum. The maximum electron exchange rate was about 2 · 106 M?1 · s?1, which is 60–70 times that for the free form at a given concentration of cytochrome c. The activation energy of the reaction for the bound cytochrome c was equal to that for the free form, being about 10 kcal/mol. The dependence of the exchange rate on temperature, cytochrome c concentration and solvent viscosity suggests that enhancement of the electron transfer rate between cytochromes c on binding to phosvitin is due to increase in the collision frequency between cytochromes c concentrated on the phosvitin molecule. 相似文献
87.
In brain tissue a spectrin-like calmodulin-binding protein calspectin, or fodrin, is concentrated in a synaptosome fraction, where most of the calspectin is associated with the synaptic membranes. This endogenous calspectin was phosphorylated by protein kinase system(s) associated with the membranes. Here, we report the solubilization and partial purification of the membrane-associated calspectin kinase activity. The activity was resolved on a gel filtration column into two fractions, peaks I and II having estimated Mr of 800 000 and 88 000. The activity of peak I was dependent on the presence of both Ca2+ and calmodulin. Peak II revealed a basal activity in the absence of Ca2+ and calmodulin, which was stimulated 2-fold by addition of Ca2+. Calmodulin had no effect on the peak II activity. 相似文献
88.
Intravenous administration of short-chain fatty acid (SCFA), such as propionate, butyrate, valerate and caproate, caused a transient increase in transmural potential difference (p.d.) across the small intestine of rat . There was a sigmoid relationship between the change in the p.d. and the logarithm of the dose of SCFA. The median effective dose of propionate, n-butyrate, n-valerate and n-caproate, which was calculated from the each dose-response curve obtained from the terminal ileum, 1.31, 1.43, 0.83 and 0.81 μmole, respectively. Repeated administrations of the same dose of propionate evoked progressively smaller response. The dose-response curve of propionate was shifted to the left by neostigmine and to the right by atropine, suggesting that the action of SCFA may be mediated by acetylcholine, which was released from a nerve ending. 相似文献
89.
The activity of a neutral protease is increased in soluble fractions from the intestine of rats after a shift from a protein-free to a casein mash and an injection of triiodothyronine. The increased activity is prevented by the administration of cycloheximide. The time curve of the response of the protease activity in intestine is similar to that of liver DNA synthesis after a shift to 50% casein and triiodothyronine. 相似文献
90.
Three polygalacturonases (PG) have been isolated from carrots(Daucus carota L. cv. Kintoki). Two were isolated from roottissues (PG-I and PG-II) and one from cell suspension cultures(PG-III). PG-I and PG-III were readily solubilized in a lowionic strength buffer, whereas PG-II required additional NaClto be solubilized. These seems to be a change in the propertiesof PG between the original tissue and carrot cell cultures.The three PGs were partially purified by chromatography on SephadexG-150, and characterized. Elution from a Sephadex G-150 column indicated a molecular weightof about 48,000 for all three PGs. PG-III, studied in detail,hydrolyzed the galacturonan chain in an exo-fashion, and wasnot activated by a variety of cations at concentrations of 0.5or 1.0 mM. The pH optimum, and pH and heat stability of PG-Iand PG-III were slightly different from those of PG-II. PG-Iwas also different from PG-II and PG-III in its pectin hydrolyzingactivity. These results indicate that the enzymatic properties of PG-IIIfrom cell cultures are very similar to those of PG-I or PG-IIfrom root tissues; the only significant difference seems tobe the binding properties of the PGs to the cell wall materials. (Received March 23, 1981; Accepted June 11, 1981) 相似文献