共查询到20条相似文献,搜索用时 15 毫秒
1.
Eric E. Bancroft Henry N. Blount Fred M. Hawkridge 《Biochemical and biophysical research communications》1981,101(4):1331-1336
The recently reported method of derivative cyclic voltabsorptometry has been applied to horse heart cytochrome at fluoride doped tin oxide optically transparent electrodes. The advantages of the derivative cyclic voltabsorptometric method compared to voltammetric methods in analytical, kinetic and mechanistic studies are discussed. 相似文献
2.
R. Rodriguez C. Lopez-Otin D. Barber J.L. Fernandez-Luna G. Gonzalez E. Mendez 《Biochemical and biophysical research communications》1982,108(1):315-321
The NH2-terminal amino acid sequence of the three anti-tumor proteins, alfa-sarcin, mitogillin and restrictocine, has been determined for 20 cycles by automated sequencing procedure. A high degree of sequence homology was observed in this region of the molecule. In addition, extensive sequence homology, ranging from 65 to 100% was found in three other carboxymethylcysteine-containing peptides isolated and sequenced from each molecule. 相似文献
3.
Toshifumi Takao Noriko Tominaga Yasutsugu Shimonishi Saburo Hara Takashi Inoue Akio Miyama 《Biochemical and biophysical research communications》1984,125(3):845-851
A heat-stable enterotoxin was isolated and purified from the culture supernatant of by reversed-phase high-performance liquid chromatography. The amino acid sequence of the purified toxin was determined to be as follows: Gln-Ala-Cys(X)-Asp-Pro-Pro-Ser-Pro-Pro-Ala-Glu-Val-Ser-Ser-Asp-Trp-Asp-Cys-Cys-Asp-Val-Cys-Cys-Asn-Pro-Ala-Cys-Ala-Gly-Cys (X: not determined). The C-terminal sequence containing 6 half-cystine residues was highly homologous to that of heat-stable enterotoxin of enterotoxigenic 相似文献
4.
L-DOPA was identified in hydrolysates of byssal adhesive discs and is present at about . The compound was isolated and purified by ion exchange on cellulose phosphate and Biogel P-2 gel filtration. Identity with standard DOPA was demonstrated using thin-layer chromatography, the effect of pH on UV absorbance, fluorescence spectrophotometry, amino acid analysis, and the preparation of ethylenediamine derivatives. Contrary to earlier reports, dityrosine was not detected. A sodium dodecylsulfate-insoluble protein containing of DOPA was isolated from the gland that secretes the disc adhesive. This protein is presumed to be a precursor of the adhesive. 相似文献
5.
R.C. Patel R. Zupcak S.A. Narang 《Biochemical and biophysical research communications》1978,85(4):1560-1567
The nine base pairs long central region of the operator gene forms a stable double helix. A comparison of melting temperatures with other biologically useful oligonucleotides indicates the importance of specific base sequence. Binding constants measured with ethidium bromide (1.7 × 105 M?1), tyrosine (4.0 × 103 M?1), and glutamine (1.5 × 103 M?1), are interpreted in terms of the involvement of a relatively small number of amino acids in the operator-repressor interaction. 相似文献
6.
C.Channa Reddy Nan-qian Li Chen-Pei D. Tu 《Biochemical and biophysical research communications》1984,121(3):1014-1020
A new glutathione -transferase has been purified to homogeneity from 105,000 × g supernatant of Sprague-Dawley rat liver homogenates. The purified enzyme exhibited specific activities of approximately 1.8, and 0.12 μmoles. min?1. mg?1 toward 1-chloro 2,4-dinitrobenzene and cumene hydroperoxide respectively. The SDS gel electrophoresis data on subunit composition revealed that the new transferase is composed of two subunits with an identical Mr of 24,400 (Yα Family). Our translation experiments with rat liver poly(A) RNAs and substrate specificity data suggest that this subunit is different from the previously reported Ya, Yb and Yc subunits of rat liver glutathione -transferases. Comparatively, the new isozyme showed significant activity toward 1,2 epoxy-3-(P-nitrophenoxy)-propane, ethacrynic acid and P-nitrophenyl acetate, 0.4, 0.34 and 0.18 μ moles. min?1. mg?1 respectively. 相似文献
7.
James B. Howard Thomas Lorsbach Lawrence Que 《Biochemical and biophysical research communications》1976,70(2):582-588
In 80% dimethyl sulfoxide/H2O, ferredoxin FeS clusters can be extruded with benzene thiol. The extruded clusters have an absorption spectra maximum at 458 nm which is characteristic of 4Fe4S centers. The amino terminal sequence of the ferredoxin has 7 of the 8 Cys residues at residue numbers 8, 11, 16, 20, 24, 39 and 42. Except for Cys 24, all of these residues can be correlated to homologous Cys residues in other bacterial ferredoxins. Although two thirds of the first 45 residues are identical to or conservative replacements for the first 43 residues of other bacterial ferredoxins, the insertion of Cys-24 indicates a major change in the environment of one of the two 4Fe4S clusters. 相似文献
8.
L-glutamate and related amino acids produced dose-related increases in cyclic GMP concentrations in cerebellar slices from 8-day old rats. The effects of L-glutamate, L-aspartate, and N-methyl-D-aspartate were antagonised in part by glutamate diethylester, while D-α-aminoadipate and DL-α-aminosuberate were ineffective. Kainic acid, although producing an effective stimulation of cyclic GMP, failed to achieve the same maximal response as glutamate, suggesting different sites of action. Cyclic GMP levels were also increased, although to a lesser extent, by L-glutamate in slices from hippocampus, medulla, hypothalamus, cortex, striatum and spinal cord of young animals. In the adult, however, this response was no longer observed. 相似文献
9.
Uzi Reiss Morton Rothstein 《Biochemical and biophysical research communications》1974,61(3):1012-1016
The temperature stabilities of pure isocitrate lyase, isolated from young and old , have been compared. The “old” enzyme shows the presence of a heat-labile component lacking in the enzyme derived from young organisms. This component has been shown to be associated with two of the five isozymes comprising the isocitrate lyase. A mechanism is proposed which might account for the presence of altered enzymes in aged organisms. 相似文献
10.
Károly Nikolics Balázs Szõke György Kéri István Teplán 《Biochemical and biophysical research communications》1983,114(3):1028-1035
The possible degradation of GnRH by intact pituitary tissue was investigated. Trypsin-, collagenase- and mechanically dispersed pituitary cells in culture and fresh pituitaries cut into eight segments were incubated with specifically tritiated GnRH or unlabeled GnRH which were detected by HPLC and RIA in incubation media. Degradation of GnRH could not be detected by either method during incubations with any of the pituitary cell cultures or fresh tissue. The results suggest that pituitary degradation is not involved in the regulation of circulating levels of GnRH. 相似文献
11.
Prabhakara V. Choudary G.Ramananda Rao 《Biochemical and biophysical research communications》1982,108(3):1293-1299
The requirement of a suitable energy source during the induced synthesis of nitrate reductase in was investigated. The levels of nitrate reductase induced were shown to be energy-dependent, and to vary in response to the type of carbon source provided. Glycerol, fructose, ethanol, glucose, and sucrose served as efficient energy sources. Growth rate of the yeast and the induced level of nitrate reductase were dependent on the ratio of carbon to nitrogen in the induction medium, and ratio of 2 being optimal. Induction of nitrate reductase was inhibited by uncouplers, 2,4-dinitrophenol (DNP), dicumarol and carbonyl cyanide -trifluoromethoxy phenyl hydrazone (CCCP), and by cyanide and azide, indicating an absolute energy-dependency. The facilitation of induction of a high level of nitrate reductase by exogenously added ATP as sole source of energy confirmed the obligate requirement of ATP for the synthesis of nitrate reductase in . 相似文献
12.
The binding of the gamma labeled neuroleptic, 77Br--bromosprioperidol, in the rat brain was examined . This binding parallels the binding of 3H-spiroperidol, in that binding is especially high in dopaminergically innervated areas, is saturable, and is displaced by high doses of unlabeled spiroperidol (1–5). Thus, 77Br--bromospiroperidol is a suitable ligand for use in gamma ray imaging techniques for monitoring of receptor binding. 相似文献
13.
It was reported in a previous study that serum estradiol-17β (E2) was elevated in rats after retrochiasmatic transection (FC). Serum E2 was also higher in estradiol cypionate treated, ovariectomized (ovx) rats that had been subjected to FC than in those that had not. This suggested that increased secretion of E2 was not the only factor responsible for elevated serum E2 after FC. To ascertain the contribution of decreased metabolism of E2 to this response, liver tissue slices were incubated with 3H-estradiol-17β, and the rates of 3h uptake and conversion to water-soluble conjugates were measured.The rate of uptake of 3H by the tissue was not indicative of the rate of conjugate formation. Livers of rats with high serum E2 exhibited lower rates of 3h uptake than those of rats with low serum E2. Even so, the formation of 3H conjugates was greater in liver of rats with high serum E2. As hypothesized, livers of rats with FC formed conjugates at a significantly lower rate than those of similarly treated rats without FC. Thus, FC of an intact rat leads to an increase in serum E2 by increasing the secretion of E2, and apparently also by decreasing the rate of E2 metabolism by the liver. 相似文献
14.
O.H. Kapp L.A. Zetye R.L. Henry S.N. Vinogradov 《Biochemical and biophysical research communications》1981,101(2):509-516
Fully oxygenated heme-containing subunits of the extracellular hemoglobin of were isolated by gel filtration in 0.05 M sodium borate, pH 9.0 at 7 ± 1°C. The polypeptide chain composition of the isolated subunits was determined by SDS PAGE. Most of the subunits exhibited reversible oxygenation curves with oxygen affinities higher than the intact hemoglobin. The Hill plots were nonlinear for hemoglobin and its subunits: the latter exhibited substantial cooperativities as evidenced by Hill constants at half-saturation in the range 2.0 to 2.8. 相似文献
15.
16.
Andreas Gescher Maurizio DIncalci Roberto Fanelli Pierluigi Farina 《Life sciences》1980,26(2):147-154
N-Hydroxymethylpentamethylmelamine (HMPMM) was identified by HPLC and by GLC-MS after derivatization, as a metabolite of the anticancer drug hexamethylmelamine (HMM) in incubation mixtures with fortified mouse liver 9000 × g and microsomal preparations. HMPMM formation was dependent on the presence of NADPH and oxygen. N-demethylated metabolites were also found. HMPMM displays appreciable chemical stability and 29% was recovered after 60 min incubation in buffer. HMPMM constituted more than 50% of total HMM metabolites in 30 min incubations. The known chemical reactivity of carbinolamines means that HMPMM could be involved in the pharmacological or toxic effects of HMM. 相似文献
17.
Jun Nagai Hirohiko Katsuki Yoshiki Nishikawa Ichiro Nakamura Teijiro Kamihara Saburo Fukui 《Biochemical and biophysical research communications》1974,60(2):555-560
The level of sterols in 4228 cells grown aerobically on a synthetic medium fortified with thiamine was significantly low compared with that in the control cells. The levels of free and esterified sterols in the thiamine-cells were 60% and 10% of the corresponding sterol levels in the control cells, respectively. Analysis by gas-liquid chromatography of non-saponifiable lipids extracted from the cells revealed that the amounts of squalene, lanosterol and two unidentified sterols were higher than those in the control cells and that ergosterol and zymosterol, major sterols in the control cells, were not present. These effects of thiamine on the content and composition of sterols were abolished by the addition of pyridoxine to the medium. 相似文献
18.
Richard Moskala C.Channa Reddy Robert D. Minard Gordon A. Hamilton 《Biochemical and biophysical research communications》1981,99(1):107-113
In the conversion of -inositol to D-glucuronic acid catalyzed by -inositol oxygenase only one atom of 18O from 18O2 is incorporated into the product, and it is found exclusively in the carboxyl group. Control experiments indicate that under the reaction conditions no exchange of solvent oxygens with D-glucuronate occurs. To avoid exchange during isolation and analysis the oxygenase product was enzymically reduced to L-gulonate and isolated in that form. The results eliminate one possible mechanism for the oxygenase reaction, but are consistent with two others which seem chemically reasonable. 相似文献
19.
The light-harvesting chlorophyll -protein complexes (LHCP) of spinach, pea, and barley thylakoids apparently contain four nonidentical polypeptide subunits of between 29,000 and 23,000 daltons on highly resolving sodium dodecyl sulfate-polyacrylamide gradient gels. Trypsin treatment of the spinach complex degraded at least the two major subunits by approximately 2000 daltons and resulted in a three-subunit pattern on gels. Proteoliposomes reconstituted with LHCP and the chloroplast diacyl lipids aggregated markedly in the presence of cations but vesicles containing LHCP prepared from trypsin-treated thylakoids did not. Amino acid analysis of native- and trypsin-treated LHCP indicated that the fragment(s) released by trypsin, which is essential for cation-induced stacking of thylakoids, contains lysine and arginine, but not aspartate or glutamate, and is thus cationic. Carboxyl groups on the surface of LHCP were charge neutralized using a water-soluble carbodiimide (1-ethyl-(3-dimethylaminopropyl)carbodiimide) plus [14C]glycine ethyl ester. Only two or three sites were labeled per 26,000-dalton polypeptide equivalent and only a minor fraction of this (22–24%) was located in the surface fragment(s) released by trypsin. Both LHCP and LHCP proteoliposomes, after carboxyl modification, aggregated avidly at low salt concentrations. The findings suggest that exposed anionic groups on the surface of LHCP contribute to an electrostatic repulsive force between membranes which must be attenuated, either by cation binding or chemical neutralization, before membrane-membrane adhesion can occur. In line with this the binding of Mn2+ by LHCP (approximately four Mn2+ bound/26,000-dalton polypeptide equivalent) was sharply decreased after carboxyl modification. 相似文献
20.
Michael G. Clark Sally D. Neville Dallas G. Clark 《Biochemical and biophysical research communications》1981,103(2):690-697
Hepatocytes were prepared from a strain of rats deficient in hepatic phosphorylase kinase and were used to assess the role of this enzyme in the adrenergic regulation of pyruvate kinase and gluconeogenesis. Epinephrine (10 μM) stimulated glucose output and gluconeogenesis from 1.8 mM lactate but did not significantly affect the concentration of hepatocyte glycogen. In addition epinephrine treatment led to an inhibition of pyruvate kinase. The stimulation of gluconeogenesis and the inhibition of pyruvate kinase by epinephrine were blocked by both α- and β-antagonists: similar effects with epinephrine were observed in cells from control animals. It is concluded that mechanisms for the adrenergic regulation of pyruvate kinase and gluconeogenesis are similar in hepatocytes from both phosphorylase kinase-deficient and normal rats. 相似文献