An enzyme which released invertase from cell ghosts of Candida utilis was isolated in an electrophoretically pure state from “Zymolyase.” The molecular weight of the purified enzyme was estimated to be 5.8 × 104, and its isoelectric point was pH 6.9. The enzyme was stable in a pH range from 6.0 to 9.0, and the optimal pH for liberation of invertase from cell ghosts was around 6.0. The activity of the enzyme was competitively inhibited by glucose, mannose, and sucrose. Unlike the starting enzyme preparation, “Zymolyase,” the purified enzyme released invertase without making holes on the surface of the cell ghosts. Various tests were applied, but the specificity of the enzyme was not defined. 相似文献
Incubating the dried cells of Brevibacterium sojae No. 425-40 in alkaline buffer, the excretion of 5′-nucleotides accompanying with the decrease of intracellular RNA was observed. Then the determination of the optimum condition of the excretion and the investigation on the enzyme responsible for the degradation of endogenous RNA were carried out.In the experiments using sonicate and disrupted cells, it appeared that orthophos-phate and Mg++ might be accelerative or essential for the degradation of endogenous RNA and, in addition to four 5′-nucleotides (AMP, GMP, UMP and CMP), each nucleoside 5′-diphosphate was also contained in its degraded products. Nucleoside 2′- or 3′-monophos-phates were not detected. Although it was not clear whether phosphodiesterase concerned with the degradation of intracellular RNA or not, it was suggested that polynucleotide phos-phorylase acted mainly on the degradation.The maximal excretion of 5′-nucleotides from dried cells was obtained by suspending 1 to 2% of dried cells in 0.05 M carbonate-bicarbonate buffer (pH 10) and incubating it at 60°C for two to three hours. Orthophosphate and Mg++ were not required for the excretion. 相似文献
Theoretical and experimental investigations were conducted on growth kinetics and substrate consumption of hydrogen bacterium Alcaligenes hydrogenophilus. The kinetic models proposed were evaluated by continuous cultures of A. hydrogenophilus under various conditions. The kinetic models closely simulated continuous cultures of A. hydrogenophilus. 相似文献
Mutants with low pyruvate dehydrogenase (PD) activities were derived from a pyruvate kinase-deficient lysine-producing mutant of Brevibacterium flavum, No. 22. They were selected as prototrophic revertants of the acetate auxotrophs of strain No. 22. Among them strain KD-11 produced 55g/liter of lysine as its HCI salt when cultured for 72 hr in a medium containing lOOg/liter of glucose, soybean-meal hydrolysate and methionine. The lysine yield of strain KD-11 was the highest ever reported (55%). The mutant required a higher concentration of methionine for maximum production and gave a smaller amount of cell mass in cultivation than its parent. PD activity of strain No. 22 was stimulated by cysteine, stabilized by glycerol, and gave apparent Kms of 89, 22, 380, 83 μM for pyruvate, coenzyme A, 3-acetylpyridine adenine dinucleotide, and NAD, respectively, under standard conditions. The apparent Km for NAD of PD from strain KD-11 was 10-times higher than that from No. 22. When the concentration of NAD was low, the cell extracts of strain KD-11 showed low PD activity. The specific activity of phosphoenolpyruvate carboxylase of strain KD-11 was slightly higher than that of strain No. 22, while the inhibition by aspartate of the former enzyme was weaker than that of the latter. 相似文献
Cerebroside was isolated from pea (Pisum sativum L.) seeds by solvent extraction, mild alkaline hydrolysis and silicic acid column chromatography. The purified material was identified as cerebroside by thin-layer chromatography and infrared spectrometry. Hydrolysates of the cerebroside were divided into fatty acid, sphingosine base and sugar fractions, and analysed, mainly by gas-liquid chromatography. The major fatty acid components were hydroxytricosanoic, hydroxydocosanoic and hydroxytetracosanoic acids. Dihydrosphingosine was the predominant sphingosine base. Only glucose was detected in the sugar fraction. Based on these results, one of the major species of pea cerebroside is suggested to be N-hydroxytricosanoyl-glucopyranosyl-dihydrosphingosine. 相似文献
Desaturation of palmitic acid was investigated in an enzyme system prepared from rat liver. 2-trans-Hexadecenoic acid as well as 9-cis-hexadecenoic acid (palmitoleic acid) were found to be formed as monoenoic acid in this system. 相似文献
A rice lamina inclination test that is simple and specific for brassinosteroids was used as a micro-quantitative bioassay for brassinolide 1 and its 6-keto congener, castasterone 2, in the concentration range of 5 x 10–5 /ig/ml to 5 x 10–3μg/ml, when uniform seedlings of the rice cultivars Arborio J-l and Nihonbare were selected. A phytohormone, indole-3-acetic acid (IAA), showed similar activity in this bioassay. Its lowest effective concentration, however, was 50 /ig/μl, about five orders of magnitude greater than that of brassinolide. Other phytohormones, abscisic acid (ABA) and the cytokinins kinetin and A6-benzyladenine, inhibited the lamina inclination of rice seedlings. The addition of a cytokinin reduced the promoting effect of brassinolide. Thus, the rice lamina inclination test can be used both as a micro-quantitative bioassay for brassinosteroids and as a method for detecting antibrassinolide compouds. 相似文献
Introduction: Patient outcomes from gastric cancer vary due to the complexity of stomach carcinogenesis. Recent research using proteomic technologies has targeted components of all of these systems in order to develop biomarkers to aid the early diagnosis of gastric cancer and to assist in prognostic stratification.
Areas covered: This review is comprised of evidence obtained from literature searches from PubMed. It covers the evidence of diagnostic, prognostic, and predictive biomarkers for gastric cancer using proteomic technologies, and provides up-to-date references.
Expert commentary: The proteomic technologies have not only enabled the screening of a large number of samples, but also enabled the identification of diagnostic, prognostic and predictive biomarkers for gastric cancer. While major challenges still remain, to date, proteomic studies in gastric cancer have provided a wealth of information in revealing proteome alterations associated with the disease. 相似文献