Aminoacyl transfer ribonucleic acid synthetases from cell-free extract of Plasmodium berghei

Aminoacyl transfer ribonucleic acid synthetases for leucine tyrosine, histidine, valine, proline, threonine, and lysine were obtainnned from cell-free extract of Plasmodium berghei. The leucyl-tRNA synthetase cane charge tRNA from liver or Escherichia coli with leucine-c(14), liver tRNA being a better substrate. The amount of aminoacylation increses linerly with respect to the quantity of tRNA added from either source and is dependent on the amount of enzyme added. The rate of aminoacylation is constant for 10 minutes and then decreases. It is enhanced by polyvinylsulfate. One-tenth millimoler pyrimethamine, hydroxystilbamidine, quinacrine, and acriflavine inhibited the formation of C(14)-valyl-tRNA. Species specificity between tRNA and its charging enzyme with respect to the recognition site is discussed.     

Native and renatured transfer ribonucleic acid

Transfer ribonucleic acid, isolated under conditions in which the original macromolecular structure is never denatured, is indistinguishable from transfer ribonucleic acid prepared by conventional methods involving denaturing steps. This finding is consistent with the absence of direct genetic control of the formation of macromolecular structure of transfer ribonucleic acid.     

Sulfur-containing nucleoside from yeast transfer ribonucleic acid: 2-thio-5(or 6)-uridine acetic acid methyl ester

A nucleoside, isolated from yeast transfer RNA, has been assigned the structure 2-thio-5-uridine acetic acid methyl ester on the basis of high-esolution mass spectrometry, chemical properties, and ultraviolet spectra. The alternate 6-substituted isomeric structure cannot yet be completely ruled out.     

酵母抽提物生产工艺的研究进展

主要阐述了酵母抽提物的定义和基本特性,并对酵母抽提物的生产方法(自溶法、酶解法和酸解法)进行了简要的介绍和比较.对酵母抽提物的一般生产工艺、前期处理工艺(啤酒酵母的脱苦、酵母破壁、自溶促进剂的选择)、自溶过程工艺(自溶时间、自溶浓度、自溶温度、外加酶、风味的改善)、下游生产工艺(澄清、质壁分离、美拉德反应、浓缩以及干燥技术)作了详细论述,预测了集营养、调味和保健于一身的酵母抽提物在食品及微生物发酵领域的发展趋势.     

Nucleotide sequence of a lysine transfer ribonucleic Acid from bakers' yeast

The nucleotide sequence of one of the two major lysine transfer RNA's from bakers' yeast has been determined. Its structure is compared to that of a lysine tRNA from a haploid yeast. A total of 21 nucleotides differ in the two molecules. Only the T-psi-C-G (thymidine-pseudouridine-cytidine-guanosine) loop and its supporting stem are identical.     

Effect of yeast extract on intestinal development and productivity of broilers

During raising of chicks, mixed feed was used animal- and plant-origin feeds and also supplementing it with 2% yeast extract NuPro, which allowed improving intestinal morphology and increasing the rate of its development and poultry productivity.     

利用残次红枣生产风味型酵母味素的工艺研究

【目的】以残次红枣为原料,对利用红枣汁培养可食性酵母菌生产作为食品调味剂的风味型酵母味素的工艺技术进行研究,为提高残次红枣加工利用率提供新思路。【方法】采用正交试验,分别对酵母菌在红枣汁中的增殖条件和营养因子对酵母菌增殖的影响进行优化;并以时间、温度、复合糖添加量和含硫化合物添加量为单因素,探讨制备风味型酵母味素的加工方法。【结果】以红枣汁作为培养基,啤酒酵母菌产蛋白质的能力高于产朊假丝酵母菌和热带假丝酵母菌,其最适增殖条件为:红枣汁可溶性固形物含量150g/kg、接种量40 mL/L、培养温度32℃、时间50h、摇床转速190r/min,NH4H2PO4、NaHSO3、MgSO4等营养因子添加量分别为0.03mol/L、0.4g/L和0.4g/L。风味型酵母味素加工方法为:在质量分数20%的啤酒酵母抽提物混合液中按25g/kg添加复合还原糖、按15g/kg添加含硫化合物,于110℃下加热60min。【结论】本试验的风味型酵母味素制备工艺操作简便、适合工厂化生产,还可提高残次红枣的利用率,并可为市场提供新型食品调味料。     

Nucleotide sequence of Escherichia coli tyrosine transfer ribonucleic acid

The nucleotide sequence of one of the Escherichia coli tyrosine-transfer ribonucleic acids was determined in order to compare its sequence with that of yeast tyrosine-transfer ribonucleic acid. Forty-four positions of both transfer ribonucleic acids are occupied by the same nucleotides if they are arranged in the manner shown here. The information obtained suggests that the conformation of transfer ribonucleic acid molecules may be a greater contributing factor than a specific nucleotide sequence in the interaction of transfer ribonucleic acid with its corresponding aminoacyl-transfer ribonucleic acid synthetase.     

Specific inhibition of viral ribonucleic acid replication by Gliotoxin

Gliotoxin inhibits intracellular replication of poliovirus in HeLa cells at a stage subsequent to adsorption and penetration of virus. The sensitive step is synthesis of viral RNA: synthesis of viral protein is unaffected except as a consequence of blockade of RNA synthesis. Concentrations of gliotoxin sufficient to block viral RNA synthesis completely do not affect cellular RNA synthesis.     

Codon recognition by enzymatically mischarged valine transfer ribonucleic acid

Direct evidence for the adaptor hypothesis has been obtained by examining the codon recognition of a purified Escherichia coli valine transfer ribonucleic acid which was enzymatically mischarged with phenylalanine labeled with carbn-14 by reaction with purified phenylalanyl-transfer ribonucleic acid synthetase from Neurospora crassa. The mischarged transfer ribonucleic acid recognized the valine codons but failed to recognize the phenylalanine codon when tested in trinucleotide-directed ribosomal binding assay.     

Sulfur: incorporation into the transfer fraction of soluble ribonucleic acid

When S(35)-labeled soluble RNA from Escherichia coli K 38 is subjected to gel filtration, four fractions of RNA are obtained by elution. Only one RNA fraction, the transfer RNA, contains sulfur, presumably as thionucleotides. Treatment with ribonuclease suggests that the incorporated sulfur is an integral part of the polynucleotide chain; digestion with alkali yields a mixture of products containing sulfur, the major one being eluted in a position similar to uridine diphosphate upon Dowex-l chromatography. Analysis by countercurrent distribution of S(35)-labeledtransfer RNA from E. coli B reveals that the incorporated sulfur is found in many RNA's that accept amino acids, but the possibility remains that not all acceptor RNA's contain sulfur.     

Facilitation of infection of monkey cells with poliovirus "ribonucleic acid"

The plaque titer of poliovirus "ribonucleic acid" on monkey kidney cells cultured in vitro is greatly increased by depleting these cells of calcium and treating the "ribonucleic acid" inoculum with a suspension of any one of several poorly water-soluble substances before inoculation. These undissolved substances apparently facilitate infection by serving as solid vehicles for the "ribonucleic acid."     

Mediation of immunity to tumor isografts in mice by heterologous ribonucleic acid

The growth of tumor isografts in inbred mice is inhibited by intra-peritoneal injections of syngeneic spleen incubated, in vitro, with ribonucleic acid extracted from guinea pigs immunized with the same mouse tumor. This inhibition is partially tumor-specific. Treatment with ribonuclease abolishes the response.     

Pyrophosphate in the 5' terminal position of a viral ribonucleic acid

A pancreatic ribonuclease digest of carbon-14-labeled Satellite Tobacco Necrosis Virus RNA was fractionated, according to charge, by column chromatography. Individual fractions were dephosphorylated with alkaline phosphomonoesterase and rechromatogramed. The fraction originally containing oligonucleotides with seven negative charges separated into two components corresponding to five and two negative charges, respectively, and therefore must have contained a terminal trinucleotide 5'-pyrophosphate, in addition to the internal hexanucleotides. Other fractions when similarly treated were found to contain only internal oligonucleotides.     

酵母抽提物主要滋味成分分析及其对鱼糜制品风味的影响

以4种酵母抽提物(KA66、FA28、KU012、FA01)为原料,通过分析其金属离子、游离氨基酸、总氨基酸和核苷酸的组成,以滋味活度值(TAV)和味精当量(EUC)为指标分别评价各滋味成分对酵母抽提物滋味的贡献程度和鲜味物质间的协同增鲜作用;并将其加入到鱼糜制品中,通过感官评价和电子鼻分析探究其对鱼糜制品风味的影响。结果表明,酵母抽提物KU012中谷氨酸、丙氨酸、5′-IMP、5′-GMP等滋味物质含量最高,TAV值最大,而FA01中丙氨酸、5′-IMP、5′-GMP含量最低,TAV值最小;FA28中总氨基酸含量最高,谷氨酸含量最高;KU012的EUC值最高,1g KU012产生的鲜味强度相当于125.22g单一味精(MSG)所产生的鲜味强度,为125.22gMSG/g;感官结果表明,酵母抽提物可显著改善鱼糜制品的滋味,对腥味也有一定掩蔽作用,KU012感官评分最高;电子鼻的结果表明,加入不同的酵母抽提物后,鱼糜制品的挥发性成分区别较大。     

酵母培养物在育肥猪中应用效果

为研究酵母培养物(YC)在育肥猪中的应用效果,选取90头健康的、体重约为60 kg的杜×长×大三元杂交猪,将其随机分为两组,每组45头。用猪场常规饲粮喂第1组(对照组)猪;在第2组(试验组)猪饲粮中添加加YC,并对其他原料比例适当调整,使2组饲粮主要养分含量相似。饲养试验周期60 d。结果表明:(1)试验组猪日均增重较对照组提高了11.84%(P0.05),饲料转化率提高3.58%(P0.05)。(2)试验组猪血糖较对照组增加了41.96%(P0.01),血清总抗氧化能力提高了17.21%(P0.01),血清谷丙转氨酶活性降低了15.05%(P0.01),血清谷草转氨酶活性降低了21.13%(P0.01),血清尿素氮减少了5.49%(P0.05),血清丙二醛降低了8.72%(P0.05)。(3)试验组猪背最长肌、肝中总超氧化物歧化酶活性较对照组分别提高了23.58%(P0.05)、6.23%(P0.05),肝中丙二醛降低了6.03%(P0.05),背最长肌滴水损失量降低了44.41%(P0.01),背最长肌亮度(L*)提高了3.57%(P0.05)。基于试验结果推断,YC可促进育肥猪生长,提高饲料转化率,改善猪体营养生化代谢,增强组织细胞稳定性,提高猪体抗氧化能力和猪肉保健价值。