以玉米麸质为原料提取L—亮氨酸

<正> 本文叙述了以玉米麸质为起始原料,制备L—亮氨酸方法。玉米麸质为我厂玉米淀粉生产的副产物。年产约2500吨,经分析,其干固物含蛋白41%,淀粉33%,脂肪8%,灰分1%,其他17%。麸质粉用95%酒精抽提,得醇溶蛋白,再用盐酸水解,其水解物用日立835—50氨基酸自动分析仪测定,各氨基酸相对含量如下:天5.4,     

以豆腐柴叶为原料提取果胶工艺研究

本文开发了一条从豆腐柴叶中提取果胶的新工艺。该工艺中,树脂吸附纯化、超滤浓缩和喷雾干燥是三个重要的单元操作。为了确定最佳提取条件和考察树脂吸附纯化和超滤浓缩两个单元操作的商业应用可行性,进行了三种不同规模的试验。结果表明,所开发的工艺在能耗和果胶质量方面明显优于传统的醇沉淀法。     

以玉米淀粉糖渣为原料制备米曲发酵酱油

以玉米淀粉糖渣为原料制备米曲,米曲中的中性蛋白酶活力能够达到4000 U/g(干基),糖化酶比活力可达到120 U/g左右,满足酿造酱油所需要求。用糖渣米曲发酵酱油,氨基态氮和总氮质量浓度分别能够达到7.1 g/L和11.9 g/L,还原糖质量浓度为13.2 g/L,各项理化指标均可达到国家二级酱油标准。     

以小什鱼为原料、提取亮氨酸的试验

L-亮氨酸又称白氨酸,是较早发现和分离出来的天然氨基酸之一。巴拉康诺特首先(1920)从羊毛水解溶液中分离出白色发亮的晶体,从而定名为亮氨酸。它广泛分布于自然界的各种蛋白质中,也有些以自由状态存在。它是人和哺乳动物营养上必需氨基酸之一。故此,必须从食物中补充,才能保持氮平衡,维持人和动物的健康和正常生长,亮氨酸在蛋白质中是分布广和含量较高的氨基酸之一,它在植物蛋白质中更为显著。     

以葡萄渣为原料,固体发酵生产单细胞蛋白的初步研究

本文报道以葡萄渣为唯一碳源,利用微生物混合培养固体发酵技术生产单细胞蛋白的初步尝试。将自分的３株霉菌、（Ａｓｐｅｒｇｉｌｕｓ）４株酵母（Ｓａｃｈａｒｏｍｙｃｅｓ）和１株细菌（Ｃｅｌｕｌｏｍｏｎａｓ）进行了不同组合的培养,并用正交试验法作了培养基配方试验,同时对培养基含水量和发酵时间也进行了一些摸索。初步结果表明,培养基在未经灭菌的条件下,以尿素为氮源,培养基含水量６０％,于２８℃—３０℃,培养４８ｈ,发酵产物的粗蛋白含量可提高一倍。     

以淀粉废液为原料生产生物农药

苏芸金杆菌(Bacillus thuringiensis)是七十年代以来,国内外生物农药中应用最广、施用面积最大的一种细菌农药。但是,以淀粉废液为主要原料,进行深层液体发酵,至今还未见国內有报道。     

以植物为原料的生态塑料

与人类一样，玉米不仅具有“指纹”，而且不同品种的“指纹”绝对不会雷同。根据这种特性，我国农业专家已成功掌握了鉴别玉米种子真伪、判断玉米种子纯度等国际尖端技术。一项科研计划表明，我国玉米标准DNA“指纹库”已进入筹备阶段。     

以菊芋为原料的生物炼制

依托新一代工业生物技术,中国科学院启动了以果糖基能源植物——菊芋为原料的生物炼制关键技术研究。2007年7月在威海召开的第二届中国资源生物技术与糖工程学术研讨会上,项目首席科学家．项目承担单位的中国科学院大连化学物理研究所研究员杜昱光介绍了以菊芋为原料的生物炼制技术。     

以农业废物为原料生产乙醇

用遗传工程方法使运动发酵单胞菌(乙醇生产量为酵母的5～6倍的革兰氏阴性厌氧菌)能够发酵的底物范围扩大了。Commission of the European Communities(CEC)的BAP项目为这项研究提供资金,旨在获得对谷类,水稻和水果进行发酵的改进方法。 在一般情况下,运动发酵单胞菌只能利用葡糖、果糖和蔗糖作为碳源,因此拓宽其可代谢的碳水化合物的范围使工业化利用成为可能。构建了含木糖分解代谢基因xy1A和xy1B的重组质粒。通过辅助接合,     

以青砖茶为原料的果茶饮料制备

以青砖茶、新鲜苹果汁、西瓜汁和菠萝汁为主要原料进行果茶饮料的研制,采用单因素试验及正交分析试验对果茶饮料的配方进行工艺优化,以感官评价和吸光值为评定指标,确定果茶饮料的最佳配方。结果表明,体积比分别为8∶2的茶汤与苹果汁的混合汁、5∶5的茶汤与西瓜汁的混合汁和3∶7的茶汤与菠萝汁的混合汁混匀调配出的茶饮料的口感最佳,色泽清透,且香气较佳。本研究为黑茶果茶饮料的研 制提供了理论依据。     

An obligatory alpha-helical amino acid residue

Stereochemical studies predict that α-amino isobutyric acid, one of the amino acids found in antibiotics, can fold only into left- or righthanded α-helical conformations. Such residues will direct chain folding and should be useful in synthetic analogs of protein sequences to increase helix stability.     

Characterization of neutral amino acid uptake by cultured epithelial cells from pig kidney

Two transport systems for neutral amino acids have been characterised in LLC-PK₁ cells. The first, which transport alanine in a sodium-dependent manner, also mediates alanine exchange and is preferentially inhibited by serine, cysteine, and α-amino-n-butyric acid. This system resembles the ASC system in Ehrlich ascites and some other cell types. There is only a small contribution of other systems to alanine uptake. The second, which transports leucine with no requirement for sodium and mediates leucine exchange, is blocked by 2-aminonorbornane-2-carboxylic acid and hydrophobic amino acids. This system is similar to the L system described in other cell types. LLC-PK₁ cells retain several other features implying renal proximal tubule origin; our results thus suggest that these transport systems may be involved in the reabsorption of neutral amino acids by the nephron in vivo.     

Diamine oxidase from pig kidney: new purification method and amino acid composition

Several methods for the isolation of apparently homogeneous pig kidney diamine oxidase have been reported in recent years (1-7), but these procedures allow to obtain only little amounts of material making very difficult the study of the molecular properties of the enzyme. Drawing useful indication from the purification procedures previously reported, we were able to set up a new method which allows to obtain homogeneous enzyme samples in high yield and with good reproducibility. This procedure allowed to determine with greater accuracy the molecular weight of the enzyme that resulted to be 170,000 daltons by gel chromatography and 145,000 by ultracentrifuge. The enzyme is composed of two apparently identical subunits and contains two copper atoms per dimer. The amino acid composition of the protein has been also worked out and found similar to those already reported for other copper dependent amine oxidases. Pig kidney diamine oxidase is a glycoprotein containing about 20% sugars by weight.     

Conformation of amino acid residue contiguous to helical polypeptide

The calculation of the conformational energy of the terminal D - or L -alanine residue contiguous to an α-helical polypeptide, polyalanine, was made. Both L -and D -residues contiguous to the carboxyl terminal of α-helical poly(L -alanine) are considered to prefer the α-helical conformation due to the effect of the α-helical structure of the polymer. The residue at the amino terminal is found to be less affected by the α-helical structure of the polymer.     

Guinea pig acylphosphatase: The amino acid sequence

We determined the primary structure of guinea pig skeletal muscle acylphosphatase, using the high degree of homology with several vertebrate acylphosphatases to obtain correct alignment of the complete series of tryptic peptides. Their sequences were obtained mainly by Edman degradation; FAB mass spectrometry was used to identify the acyl group blocking the NH₂-terminal residue and to elucidate the structure of the NH₂-terminal tryptic peptide. The comparison among acylphosphatase sequences from skeletal muscle of several vertebrate species is presented and discussed.     

A functional arginine residue in NADPH-dependent aldehyde reductase from pig kidney.

Pig kidney aldehyde reductase is inactivated by 2,3-butanedione, phenylglyoxal, methylglyoxal, and 1,2-cyclohexanedione. 2,3-Butanedione caused the most rapid loss in enzyme activity, the rate of loss being proportional to the concentration of 2,3-butanedione. Neither D-glyceraldehyde nor pyridine 3-aldehyde, both substrates for this broadly specific enzyme, protected the enzyme from inactivation but 1 mM NADPH or NADP completely prevented the loss of activity by 2,3-butanedione suggesting the involvement of arginine in the binding of cofactor. Nicotinamide mononucleotide (NMN) (reduced form) offered no protection to inactivation whereas ADP-ribose phosphate gave complete protection indicating that it is the latter portion of NADPH which interacts with the essential arginine. Both NMN and ADP-ribose phosphate are competitive inhibitors of aldehyde reductase with respect to NADPH. Butanedione-modified aldehyde reductase could still bind to a blue dextran-Sepharose 4B column suggesting that the modified arginine did not bind NADPH. This was confirmed by fluorescence spectra which showed that chemically modified aldehyde reductase caused the same blue shift of NADPH fluorescence as did native aldehyde reductase. Of additional interest was the quenching of NADPH fluorescence by aldehyde reductase which, with one exception, is in contrast to the fluorescence behavior of all other oxidoreductases.     

New scoring matrix for amino acid residue exchanges based on residue characteristic physical parameters

Based on residue characteristic physical parameters, a new scoring matrix, called EMPAR, for amino acid exchanges in proteins was obtained. When comparing protein sequences for detecting homologies, the use of this matrix in place of the Dayhoff log-odds matrix yields results that reflect the topological similarities in the proteins. The use of EMPAR is equivalent to the parametric correlates coefficient approach of Ooi and his colleagues. This matrix correlates at 0.63 with the Dayhoff matrix.