营养缺陷型酿酒酵母AY生长代谢的热动力学研究

用微量热法研究了尿嘧啶缺陷型酿酒酵母AY,和该菌株分别经穿梭质粒pYLZ-2、重组质粒pYLZ-2/f27、pYLZ-2/622转化的3种菌株的生长代谢热动力学.尿嘧啶缺陷型酿酒酵母AY在基本培养基中不生长,没有代谢热效应产生,而在葡萄糖蛋白胨培养基和丰富营养培养基(YPD)中生长,并且在YPD中生长最好;向基本培养基中加入尿嘧啶后,AY能够生长,而且随着尿嘧啶浓度的增加,其生长速率常数增大;经质粒转化的3个菌株均能在基本培养基中生长,代谢产热曲线各不相同,与转入质粒的结构、功能密切相关.研究结果表明了各菌株遗传特征的差异.     

营养缺陷型酿酒酵母AY生长代谢的热动力学研究

用微量热法研究了尿嘧啶缺陷型酿酒酵母AY,和该菌株分别经穿梭质粒pYLZ2、重组质粒pYLZ2/f27、pYLZ2/622转化的3种菌株的生长代谢热动力学.尿嘧啶缺陷型酿酒酵母AY在基本培养基中不生长,没有代谢热效应产生,而在葡萄糖蛋白胨培养基和丰富营养培养基(YPD)中生长,并且在YPD中生长最好;向基本培养基中加入尿嘧啶后,AY能够生长,而且随着尿嘧啶浓度的增加,其生长速率常数增大;经质粒转化的3个菌株均能在基本培养基中生长,代谢产热曲线各不相同,与转入质粒的结构、功能密切相关.研究结果表明了各菌株遗传特征的差异.     

Study on Inhibitors of Methionine Synthase Ⅷ: Synthesis of 2,5-Diamino-4-oxo-6- (3-butenyl) pyrimidine

Cobalamin-dependent methionine synthase plays a crucial role in folate metabolism and such would appear to be an excellent target for rational antifolate drug design. However, to date, no anticancer agents directed at this enzyme are available, but the enzyme is efficiently and specifically inhibited by N2O and this has proven invaluable for evaluating the biochemical consequence of enzyme inhibition and for mechanistic studies. [1,2] 2,5-Diamino-4-oxo-6-(3-butenyl) pyrimidine, a key intermediate in synthetic inhibitors of methionine synthase, was first synthesized using γbutenyl-β-ketoester and guanidine carbonate (Scheme 1). [3]     

3,4-去氢-3-羟基-4-苯基-2,5-吡喃二酮的合成

Merck研究小组于1999年报道了一类醌类化合物具有类似胰岛素的作用[1],体内口服给药具有显著的降糖作用,目前在治疗糖尿病方面极具前景。其中3,4 去氢 3 羟基 2,5 吡喃二酮(3)是合成这类醌类化合物的重要中间体。本文报道了该中间体3,4 去氢 3 羟基 4 苯基 2,5 吡喃二酮的合成。合成路线如下图所示。其中化合物的结构均通过熔点、MS、IR、1HNMR确证。1　实验部分1 1　仪器与试剂XRC 1型显微熔点仪测定(温度计未经校正),四川大学科仪厂;Nicolet200SXV傅立叶变换红外光谱仪(石蜡油油湖法),Nicolet公司制造;FinniganLCQDECA型质…     

The mechanism of the photochemical transformations of 2,5-di-tert-butyl-6-hydroxy-6-methylcyclohexa-2,4-dienone

When exposed to visible light, 2,5-di-tert-butyl-6-hydroxy-6-methylcyclohexa-2,4-dienone undergoes rearrangements in several steps. The first, photochemical step involves contraction of the six-membered ring to a five-membered cyclic ketol. Its subsequent rearrangements follow a number of parallel pathways. The main pathway involves the formation of an unstable intermediate bicyclo[3.1.0]hexenone derivative, whose further transformation leads to 4-acetylcyclopentenone via opening of the three-membered ring in a deaerated solution or to a bicyclic peroxide in the presence of air. In addition, a parallel bimolecular reaction of the five-membered ketol yields sterically hindered 2-acetylcyclopentenone.     

The rearrangement of some 2-substituted-4-bromo-2,5-dinitro-6-hydroxy-3,6-dimethylcyclohex-3-en-1-ones

In chloroform at 20°, or in tetrachloroethylene at 120°, the title compounds (1) rearrange to give the α-diketone(2), the structure of which was determined by X-ray crystal structure analysis; a possible rearrangement mechanism is outlined.     

2,5-二甲基-4-羟基-3(2H)呋喃酮的合成

以乙酰丙酮(1)为原料，经电解氧化偶联，Paal-Knorr闭环，Baeyer-Villiger氧化，水解等步骤，合成了一种重要的杂环香料，2,5-二甲基-4-羟基-3(2H)呋喃酮(6)。     

Isolation of a Dosage Dependent Lethal Mutation in Ubiquitin Gene of Saccharomyces Cerevisiae

Summary: Ubiquitin is a small protein with a highly conserved sequence, playing a pivotal role in ubiquitin proteasome system (UPS). Considering the central role UPS has in cellular homeostasis, several drugs have been developed to target UPS to remove cells responsible for cancer and other neurodegenerative diseases. As an alternative to the above approach, in the present study we have isolated dose dependent lethal form of ubiquitin gene by in vitro evolution. In vitro evolution is a powerful tool for developing proteins with novel and desirable properties. The ubiquitin gene of Saccharomyces cerevisiae was subjected to in vitro evolution and lethal mutations were selected. The ubiquitin of S. cerevisiae differs only by three residues from human ubiquitin. The mutants were selected by expressing the protein in temperature sensitive ubi4 deletion mutants of ubiquitin. Most of the mutations in ubiquitin gene failed to complement UBI4 phenotype under heat shock. Only one of the mutants caused cell lysis, even at permissive temperature. Interestingly, expression of the same protein in wild type S. cerevisiae cells left them unaffected, establishing the mutant protein as a competitive inhibitor for UPS. Sequencing of the mutant gene showed four completely novel amino acid substitutions. They are namely, Ser20 to Phe, Ala46 to Ser, Leu50 to Pro and Ile61 to Thr. Construction of the mutant ubiquitin gene and characterization of the mutant phenotype along with the nature and location of the mutations are presented.     

Crystal and molecular structures of 4-acetamido-2,6-dibromo-4-hydroxy-1,2-dimethoxycyclohexa-2,5-diene

A complete x-ray investigation has been made of 4-acetamido-2,6-dibromo-4-hydroxy-1,1-dimethoxycyclohexa-2,5-diene, isolated from the marine spongeVerongia gigantea. It has been shown that the orientation of the acetamide group in the molecule is stabilized by an intramolecular O-H... O hydrogen bond with the hydroxy group.Pacific Ocean Institute of Bioorganic Chemistry, Far-Eastern Branch, Russian Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 215–218, March–April, 1992.     

Microbiological synthesis of 4-hydroxy-5-isopropyl-5-methoxy-2-oxo-2,5-dihydrofuran

M. V. Lomonosov Moscow State University, Moscow 119899, and Chemistry Section, Leipzig University, 7062 Leipzig, Germany. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 711–712, May, 1994.     

2-二乙氨基-4-羟基-6-甲基嘧啶的合成

二乙基胍硝酸盐;硝酸盐;BTEA;2-二乙氨基-4-羟基-6-甲基嘧啶的合成     

The formation and thermal decomposition of 4-hydroperoxy-2-hydroxy-3,4,6-triisopropylcyclohexa-2,5-dienone

Auto-oxidation of 3,4,6-triisopropylcatechol affords crystalline 2-hydroxy-4-hydroperoxy-3,4,6-triisopropylcyclohexa-2,5-dienone. Thermal decomposition of the resulting hydroperoxide was carried out and the reaction products were determined. The decomposition mainly proceeds by a route without cleavage of the O—O bond, unusual for hydroperoxides, to give the starting 3,4,6-triisopropylcatechol and 3,4,6-triisopropylbenzo-1,2-quinone. The hydroperoxide decomposes in part according to the traditional pattern involving the O—O bond cleavage to give 3-hydroxy-2,5-diisopropylbenzo-1,4-quinone.     

Production and Characterization Te-Peptide by Induced Autolysis of Saccharomyces Cerevisiae

Recently, the interest in mimicking functions of chalcogen-based catalytic antioxidants like selenoenzymes, has been increased. Various attempts had been done with selenium, but very few attempts were carried out with tellurium. Bio-complex formation and characterization of tellurium was not tried earlier by using any organism. The present study was focused on tellurium peptide production, characterization, and bioactivity assessment especially Mimetic to glutathione peroxidase (GPx). The production was achieved by the autolysis of total proteins obtained from Saccharomyces cerevisiae ATCC 7752 grown with inorganic tellurium. The GPx-like activity of the hydrolyzed tellurium peptide was increased when prepared by autolysis, but decreased when prepared by acid hydrolysis. Tellurium peptide produced by autolysis of the yeast cell showed increased GPx-like activity as well as tellurium content. Tellurium peptide showed little toxicity, compared to highly toxic inorganic tellurium. The results showed the potential of tellurium peptide as an antioxidant that can be produced by simple autolysis of yeast cells.     

Stereochemical effects in the mass spectra of 2-hydroxy-, 5-hydroxy- and 2,5-dihydroxyprotoadamantanes

Electron ionization and methane and isobutane chemical ionization mass spectra have been obtained for the four configurationally isomeric 2,5-protoadamantanediols and the corresponding model monoalcohols. Although the electron impact (both 70 and 15 eV) and methane chemical ionization mass spectra of the 2,5-protoadamantanediols are distinct, the variations are not large and in general they are difficult to rationalize in terms of specific structural features. In contrast, the isobutane chemical ionization mass spectra of these diols show significant differences which can easily be correlated with sterochemical orientations of the substituents.