Glutathionylation of lens proteins through the formation of thioether bond

Formation of lanthionine, a dehydroalanine crosslink, is associated with aging of the human lens and cataractogenesis. In this study we investigated whether modification of lens proteins by glutathione could proceed through an alternative pathway: that is, by the formation of a nonreducible thioether bond between protein and glutathione. Direct ELISA of the reduced water-soluble and water-insoluble lens proteins from human cataractous, aged and bovine lenses showed a concentration-dependent immunoreactivity toward human nonreducible glutathionyl-lens proteins only. The reduced water-insoluble cataractous lens proteins showed the highest immunoreactivity, while bovine lens protein exhibited no reaction. These data were confirmed by dot-blot analysis. The level of this modification ranged from 0.7 to 1.6 nmol/mg protein in water-insoluble proteins from aged and cataractous lenses. N-terminal amino acid determination in the reduced and alkylated lens proteins, performed by derivatization of these preparations with dansyl chloride followed by an exhaustive dialysis, acid hydrolysis and fluorescence detection of dansylated amino acids by RP-HPLC, showed that N-terminal glutamic acid was present in concentration of approximately 0.2 nmol/mg of lens protein. This evidence points out that at least some of the N-terminal amino groups of nonreducible glutathione in the reduced human lens proteins are not involved in a covalent bond formation. Since disulfides were not detected in the reduced and alkylated human lens proteins, GSH is most likely attached to lens proteins through thioether bonds. These results provide, for the first time, evidence that glutathiolation of human lens proteins can occur through the formation of nonreducible thioether bonds.     

Hydrocarbons,free fatty acids,and amino acids of sclerotia of Sclerotinia sclerotiorum

Summary Sclerotia of Sclerotinia sclerotiorum (Lib.) D By. were obtained from commercial pea-and bean-cleaning operations or grown on potato-dextrose agar and synthetic glucose-and sucrose-salts agar media. The crude fat (ether extract) content of sclerotia varied from 0.8 to 1.5%. Extraction and fractionation of the lipids followed by gas chromatographic analysis showed that sclerotia from pea cleanings contained one predominant hydrocarbon which was absent from sclerotia produced in the laboratory. Sclerotia from natural sources and grown in the laboratory contained a similar distribution of C₁₈ unsaturated free fatty acids, however, quantitative differences were noted. Palmitic, oleic and linoleic were the major free fatty acids of the laboratory-grown sclerotia while a high proportion of linoleic acid was also found in sclerotia from natural sources. Sclerotia were fractionated into water-soluble and water-insoluble fractions. After acid hydrolysis of the waterinsoluble fraction, both fractions were analyzed for amino acids. Twenty-one compounds, including 2 unknowns, were detected in the soluble fraction. The hydrolyzates contained 19 amino acids, including the same 2 unknowns. Two compounds tentatively identified as ornithine and -aminobutyric acid were found only in the water-soluble fraction. The relative amino acid composition of the water-insoluble fraction of sclerotia from various sources was fairly constant but the arginine content decreased on the synthetic media.     

Effect of products from heated amino acids on conductance in lipid bilayer membranes and non-aqueous solvents

The electrical conductance of lipid bilayer membranes of oxidized cholesterol is elevated 10²–10³ times by the addition of various products of the heating of amino acids. Solution of such products in chloroform yields a greater increase in conductance. The results are obtained with both water-soluble and water-insoluble fractions. They are discussed in the context of the origin of electroconductive tissue.     

D- and l-amino acid concentrations in culture broth of Lactobacillus are highly dependent on the phylogenetic group of Lactobacillus

d-amino acids produced by Lactobacillus are thought to contribute to the taste quality and health functions; however, no studies have comprehensively evaluated the concentrations of the D- and L-forms of amino acids separately in individual Lactobacillus strains. To gain insight into amino acid concentrations in Lactobacillus, we evaluated amino acid concentrations in culture broth of Lactobacillus separately for the D- and L-forms. Lactobacillus strains were cultured in culture broth, and the amino acid concentrations in supernatant were assessed. The amino acid concentrations obtained by liquid chromatography-tandem mass spectrometry (LC-MS/MS) were subjected to cluster analysis based on Bray-Curtis distance with Ward's minimum variance method. In the analysis of amino acid concentrations under culture with different monosaccharides, the distances among strains cultured with the same monosaccharide were significantly greater than those among cultures of the same strain under different monosaccharides (p < 0.01). The cluster analysis of amino acid concentrations under culture with the same monosaccharide suggested that strains belonging to the same phylogenetic group of Lactobacillus exhibited similar concentrations of amino acids. Data analyses of 70 strains belonging to 17 Lactobacillus taxa indicated that the concentrations of amino acids were highly dependent on the phylogenetic group of Lactobacillus and that the group differences in amino acid concentration were strongly driven by differences in l-serine and d-alanine concentrations. Our results indicate that it is important to evaluate D- and l-amino acids separately when evaluating variations in amino acid concentrations. Because d-alanine has the potential to affect taste quality, the results of this study may provide insight into the taste quality of fermented food produced by Lactobacillus.     

青杨脊虎天牛的危害与杨树氨基酸组成和含量的相关性

为了研究不同品种杨树上青杨脊虎天牛Xylotrechus rusticus L.的危害与树木氨基酸组成和含量之间的相关性,利用HPLC柱前AccQ·Tag衍生法,分析35 a小青杨、24 a 小青×黑杨、24 a 小黑杨、16 a 香杨、27 a和40 a小叶杨的韧皮部和木质部中氨基酸的组成及相对含量。在各杨树品系主干2.5 m高处,韧皮部共检测出15种氨基酸：丙氨酸、精氨酸、天冬氨酸、半胱氨酸、胱氨酸、谷氨酸、甘氨酸、异亮氨酸、亮氨酸、赖氨酸、苯丙氨酸、脯氨酸、丝氨酸、苏氨酸和组氨酸;木质部氨基酸种类与韧皮部的相近,区别在于木质部缺少组氨酸,多了缬氨酸。各杨树品系韧皮部同种氨基酸的相对含量差异显著,但与青杨脊虎天牛危害株率无紧密相关性;木质部中同种氨基酸相对含量差异显著,且与青杨脊虎天牛危害株率呈显著正相关。结果提示杨树木质部氨基酸相对含量越高,越利于天牛幼虫的生长发育。小青杨中氨基酸种类齐全、含量均衡,其株被害率高达84%;小黑杨木质部氨基酸种类和相对含量都较贫乏,香杨的氨基酸种类不全,且相对含量不均衡,二者均不受青杨脊虎天牛危害。不同部位株被害率的差异与氨基酸的相对含量无关,可能与青杨脊虎天牛只在老树皮裂缝处产卵的习性有关。     

Structure-based statistical analysis of transmembrane helices

Recent advances in determination of the high-resolution structure of membrane proteins now enable analysis of the main features of amino acids in transmembrane (TM) segments in comparison with amino acids in water-soluble helices. In this work, we conducted a large-scale analysis of the prevalent locations of amino acids by using a data set of 170 structures of integral membrane proteins obtained from the MPtopo database and 930 structures of water-soluble helical proteins obtained from the protein data bank. Large hydrophobic amino acids (Leu, Val, Ile, and Phe) plus Gly were clearly prevalent in TM helices whereas polar amino acids (Glu, Lys, Asp, Arg, and Gln) were less frequent in this type of helix. The distribution of amino acids along TM helices was also examined. As expected, hydrophobic and slightly polar amino acids are commonly found in the hydrophobic core of the membrane whereas aromatic (Trp and Tyr), Pro, and the hydrophilic amino acids (Asn, His, and Gln) occur more frequently in the interface regions. Charged amino acids are also statistically prevalent outside the hydrophobic core of the membrane, and whereas acidic amino acids are frequently found at both cytoplasmic and extra-cytoplasmic interfaces, basic amino acids cluster at the cytoplasmic interface. These results strongly support the experimentally demonstrated biased distribution of positively charged amino acids (that is, the so-called the positive-inside rule) with structural data.     

The amino acid composition of proteins from anaerobic halophilic bacteria of the order Halanaerobiales

We performed a comparative analysis of the genome sequences of three anaerobic halophilic fermentative bacteria belonging to the order Halanaerobiales: Halanaerobium praevalens, the alkaliphilic "Halanaerobium hydrogeniformans", and the thermophilic Halothermothrix orenii to assess the amino acid composition of their proteins. Members of the Halanaerobiales were earlier shown to accumulate KCl rather than organic compatible solutes for osmotic balance, and therefore the presence of a dominantly acidic proteome was predicted. Past reports indeed showed a large excess of acidic over basic amino acids in whole-cell hydrolysates of selected members of the order. However, the genomic analysis did not show unusually high contents of acidic amino acids or low contents of basic amino acids. The apparent excess of acidic amino acids in these anaerobic halophiles reported earlier is due to the high content in their proteins of glutamine and asparagine, which yield glutamate and aspartate upon acid hydrolysis. It is thus suggested that the proteins of the Halanaerobiales, which are active in the presence of high intracellular KCl concentrations, do not possess the typical acidic signature of the 'halophilic' proteins of the Archaea of the order Halobacteriales or of the extremely halophilic bacterium Salinibacter.     

显齿蛇葡萄基本成分研究

对显齿蛇葡萄（Ampelopsis grossdentata)幼嫩茎叶中的粗蛋白,水溶性蛋白,氨基酸组分,总灰分,无机营养元素,多酚,水提取物,总黄酮以及其中的二氢杨梅素含量作了测定,结果表明：显齿蛇葡萄幼嫩茎叶中粗蛋白氨基酸及无机营养元素含量丰富,多酚,水提取率,总黄酮和二氢杨梅素含量高。显齿蛇葡萄幼嫩茎叶既可粗加工为具特殊风味的类茶产品,又可作集营养,保健,药用功能于一体的资源加以深度开发。     

Asymmetric amino acid compositions of transmembrane beta-strands

In contrast to water-soluble proteins, membrane proteins reside in a heterogeneous environment, and their surfaces must interact with both polar and apolar membrane regions. As a consequence, the composition of membrane proteins' residues varies substantially between the membrane core and the interfacial regions. The amino acid compositions of helical membrane proteins are also known to be different on the cytoplasmic and extracellular sides of the membrane. Here we report that in the 16 transmembrane beta-barrel structures, the amino acid compositions of lipid-facing residues are different near the N and C termini of the individual strands. Polar amino acids are more prevalent near the C termini than near the N termini, and hydrophobic amino acids show the opposite trend. We suggest that this difference arises because it is easier for polar atoms to escape from the apolar regions of the bilayer at the C terminus of a beta-strand. This new characteristic of beta-barrel membrane proteins enhances our understanding of how a sequence encodes a membrane protein structure and should prove useful in identifying and predicting the structures of trans-membrane beta-barrels.     

冬虫夏草菌菌丝体中的氨基酸及其衍生物的代谢组学分析

为探究冬虫夏草菌（Ophiocordyceps sinensis）菌丝体氨基酸及其衍生物的差异性,采用超高效液相色谱串联质谱（Ultra performance liquid Chromatography, tandem mass spectrometry, UPLC-MS/MS）技术对3株冬虫夏草菌（玉树菌株XSH、达日菌株DR、贵德菌株LJ）菌丝体的氨基酸及其衍生物进行靶向定量检测,利用主成分分析（Principal component analysis, PCA）和正交偏最小二乘判别分析（Orthogonal signal correction and partial least squares-discriminant analysis, OPLS-DA）考察样品分类情况、筛选差异代谢物。结果表明,3株菌株菌丝体中均检测到72种氨基酸及其衍生物,发现除组氨酸外可合成蛋白质的19种氨基酸,菌株XSH的总氨基酸及必需氨基酸绝对含量均高于其他菌株。菌株XSH相比菌株DR和菌株LJ分别含有29种和28种差异氨基酸及其衍生物,菌株DR相比菌株LJ含有10种差异氨基酸及其衍生物,此外,3株菌株菌丝体含有3个共有的差异氨基酸及其衍生物,分别为高精氨酸、N-乙酰-L-谷氨酰胺、肌氨酸。京都基因与基因组百科全书（Kyoto encyclopedia of genes and genomes,KEGG）通路富集分析显示,差异氨基酸及其衍生物在精氨酸和脯氨酸代谢通路中更活跃,不同产区冬虫夏草菌株的氨基酸含量可能受精氨酸和脯氨酸代谢通路的影响。基于研究结果发现不同产区的冬虫夏草菌株的氨基酸及其衍生物存在较大的差异。     

小菜蛾感染球孢白僵菌后血淋巴游离氨基酸的测定

通过高效液相色谱（HPLC）对感染球孢白僵菌后小菜蛾血淋巴游离氨基酸含量进行测定,结果表明染菌后小菜蛾幼虫体内氨基酸含量明显低于对照组,主要是由于菌株在虫体内营养生长消耗和虫体内的养分所致;小菜蛾幼虫体内具有菌株营养生长所必需的氨基酸,因此可以认为小菜蛾是白僵菌的敏感寄主;各处理组间各种游离氨基酸在量上存在一定的差异,是由于不同发育阶段的虫体与菌株及不同类型菌株营养生长所必需的游离氨基酸含量不同所造成的。     

Effect of mercury on selenium binding to rat lens proteins in vitro

The effect of mercury in the incubation medium on selenium influx, efflux and distribution was studied in eye lenses of 14-day-old rats. The presence of mercury did not affect the uptake of selenium into a water-soluble protein fraction but increased considerably its content in water-insoluble proteins and thus also the selenium influx into experimental lenses. The efflux from experimental lenses yielded significantly lower amounts of released selenium, most of the selenium being bound to proteins. In contrast, efflux experiments with control lenses showed most of the selenium to be in the medium in the form of free anions. The selenium content in experimental lenses decreased after the efflux only in the fraction of water-soluble proteins, while the decrease in control lenses was found in both fractions and was relatively higher in water-insoluble proteins. During both influx and efflux experiments the lenses of both groups released a small of proteins, but no difference found between the two groups.     

Coat proteins of strains of two RNA viruses: comparison of their amino acid sequences

Summary The amino acid sequences of four strains of tobacco mosaic virus isolated in different parts of the world are compared. The differences between the strains are discussed with respect to special proteinchemical features (such as beginning of the chain, deletion of amino acids, number of different amino acids, sizes and distribution of regions with invariable amino acids) and with respect to the possibility of deducing the most probable nucleotide sequence for the coat protein cistron of tobacco mosaic virus.The complete amino acid sequences of the two RNA bacteriophage strains fr and f₂ are compared. According to their coat proteins three groups of phages can be formed: 1) MS 2, f₂ M 12 and R 17, 2) fr and 3) Q.     

Occurrence of UV-Absorbing, Mycosporine-Like Compounds among Cyanobacterial Isolates and an Estimate of Their Screening Capacity

A survey of 20 strains of cyanobacteria (belonging to 13 genera) isolated from habitats exposed to strong insolation revealed that 13 strains contained one or more water-soluble, UV-absorbing, mycosporine amino acid (MAA)-like compounds. Some of the compounds were identical in several strains. In all, 13 distinct compounds were found. The UV absorption spectra of MAAs complemented well that of the extracellular sunscreen pigment scytonemin, which many of the strains also produced. Even though the specific MAA contents were variable among strains, they were invariably higher when the cultures were grown with UV radiation than when it was absent. In five strains tested, the MAA complement accumulated as a solute in the cytoplasmic cell fraction. The sunscreen capacities of MAA and scytonemin and their combined capacity were estimated for each strain and condition on the basis of the specific contents, cell size, and cellular location of the compounds. The estimates suggested that significant, albeit not complete, protection from UV photodamage could be gained from the possession of either MAA or scytonemin but especially from simultaneous screening by both types of compounds.     

Two pools of glycogen in Saccharomyces.

The effect of different extraction procedures on the yields of water-soluble and water-insoluble glycogen fractions from a number of Saccharomyces strains was studied by using a specific method for glycogen determination. The similarity of the yields obtained by the different procedures showed that neither form of glycogen is an artifact, and variations in the relative amounts of glycogen in the two fractions during cell growth and in different yeast strains suggest that they represent different pools of storage material with specific roles in cell development and differentiation. A proportion of the water-insoluble glycogen fraction, solubilized by mechanical agitation, was shown to be strongly associated with a beta-glucan-like polysaccharide that may be a cell wall component.     

Complete nucleotide sequence of wild-type hepatitis A virus: comparison with different strains of hepatitis A virus and other picornaviruses.

The complete nucleotide sequence of wild-type hepatitis A virus (HAV) HM-175 was determined. The sequence was compared with that of a cell culture-adapted HAV strain (R. Najarian, D. Caput, W. Gee, S.J. Potter, A. Renard, J. Merryweather, G.V. Nest, and D. Dina, Proc. Natl. Acad. Sci. USA 82:2627-2631, 1985). Both strains have a genome length of 7,478 nucleotides followed by a poly(A) tail, and both encode a polyprotein of 2,227 amino acids. Sequence comparison showed 624 nucleotide differences (91.7% identity) but only 34 amino acid differences (98.5% identity). All of the dipeptide cleavage sites mapped in this study were conserved between the two strains. The sequences of these two HAV strains were compared with the partial sequences of three other HAV strains. Most amino acid differences were located in the capsid region, especially in VP1. Whereas changes in amino acids were localized to certain portions of the genome, nucleotide differences occurred randomly throughout the genome. The most extensive nucleotide homology between the strains was in the 5' noncoding region (96% identity for cell culture-adapted strains versus wild type; greater than 99% identity among cell culture-adapted strains). HAV proteins are less homologous with those of any other picornavirus than the latter proteins are when compared with each other. When the sequences of wild-type and cell culture-adapted HAV strains are compared, the nucleotide differences in the 5' noncoding region and the amino acid differences in the capsid region suggest areas that may contain markers for cell culture adaptation and for attenuation.     

Polymorphism of water-soluble and triton-X 100-extractable esterases and proteins from Leptospira]

Electrophoresis in gel from polyacrylamide was used to study the water-soluble intracellular esterases, triton-X 100-extracted and proteins of three saprophytic and three pathogenic strains of leptospirae belonging to different serological types. The results of investigation of a relative mobility of 27 fractions with an esterasic activity and the molecular weight of eight of them showed that their polymorphism was mainly consecuent of structural differences. In examination of proteins extracted from the cell residues with triton-X 100 there was also revealed an intertype polymorphism: by acrylamide electrophoresis with sodium dodecylsulphate they were divided into 3--10 fractions with a molecular weight of from 20000 to 200000. The results of these studies are discussed as a manifestation of biochemical individuality of leptospirae of individual serological types.     

Taxonomic variation in total leaf protein amino acid compositions of grasses

Leaves of greenhouse grown grasses had free protein amino acid contents of generally less than 5 % total amino acids, while field collected grasses averaged 14.7 % free protein amino acid contents. Taxonomic patterns are detectable in the total leaf amino acid profiles of grasses from both sources, those of pooids being distinguishable from those of chloridoids and panicoids, and those of danthonioids showing an intermediate pattern. Leaf profiles of Oryza, Stipeae, and Ehrharteae resemble one another, and are more like those of pooids than those of panicoids. Variations in Thr and Leu are apparently associated with differences in photosynthetic pathway. Grass leaves are generally low in total amino acid contents (2.2 ? 1.0 g % fr. wt), with Ile, Val and Met + Cys identified as the limiting essential amino acids. However, the nutritional ‘chemical scores’ of grass leaf proteins are high (75 %, based on the WHO scoring pattern).     

野蚕黑卵蜂寄主识别利它素的纯化及氨基酸组成分析

针对利它素特殊的物理及化学性质 ,采用特定的温度分离方法 ,成功地从野蚕Theophilamandarina和家蚕Bombyxmori的雌蛾性附腺中分别获得了纯度较高的野蚕黑卵蜂Telenomustheophilae寄主识别利它素。对这两种利它素氨基酸组成的分析表明 ,来自家蚕和野蚕雌蛾性附腺的利它素在氨基酸的组成和含量方面非常相似 ,在检测到的 15种氨基酸中 ,甘氨酸、谷氨酸和天冬氨酸的克分子百分数在 10 %以上。从家蚕得到的分别为 2 8 1%、 18 5 %和 12 6 %。从野蚕得到的分别为 2 4 4%、18 1%和 10 1%。这 3种氨基酸之和在家蚕和野蚕中均超过 5 0 %以上。用凝胰乳蛋白酶对这两种利它素进行水解时发现溶液中均产生非水溶性沉淀 ,电泳表明沉淀的多肽蛋白分子量在 10kD左右。这显示在野蚕和家蚕利它素结构中 ,有着与家蚕丝蛋白相类似的结构 ,存在着结晶区域 (沉淀 )和无定形区域 (上清 )。     

几种海洋微藻的氨基酸含量

分析测定分属硅藻,绿藻和蓝藻的７种海洋饵料微藻氮和氨基酸含量。氮含量范围为４．０４％～９．８６％,总氨基酸中共测出１７种氨基酸,含量范围为１．２３％～９．７４％。名藻的总氨基酸含量顺序与氮含量相同