A New Hybrid Model of Amino Acid Substitution for Protein Functional Classification

In this paper, a new hybrid model of amino acid substitution is developed and compared with the others in previous works. The results show that the new hybrid model can characterize the protein sequences very well by calculating Fisher weights, which can denote how much the variants contribute to the classification.

Computational Study for the Aromatic Nucleophilic Substitution Reaction on 1-Dimethylamino-2,4-bis(trifluoroacetyl)-naphthalene with Amines

Our previous research showed that aliphatic amines were put in order of high reactivity as “ethylamine > ammonia > t-butylamine > diethylamine” on the aromatic nucleophilic substitution of 1-dimetylamino-2,4-bis(trifluoroacetyl)-naphthalene 1 in acetonitrile. The DFT calculation study (B3LYP/6-31G* with solvation model) for the reactions of 1 with above four amines rationally explained the difference of each amines reactivity based on the energies of their Meisenheimer complexes 3 which are assumed to formed as the reaction intermediates in the course of the reaction giving the corresponding N-N exchange products 2. Intramolecular hydrogen bond between amino proton in 1-amino group and carbonyl oxygen in 2-trifluoroacetyl group stabilizes Meisenheimer complexes 3 effectively, and accelerates the substitution reaction from 1 to 2. Our calculation results also predicted that the above order of amines is also true if less polar toluene is used as a solvent instead of acetonitrile even though more enhanced conditions are required.

5-取代-4-氨基-3-巯基-1,2,4-三唑衍生物的应用进展

5-取代-4-氨基-3-巯基-1,2,4-三唑是一类重要的五元杂环化合物,由于分子中含有巯基和伯胺基两个活性基团,既可以单个基团参与反应生成N-或S-取代产物,又可以同时发生反应生成稠杂环化合物。由其衍生而来的化合物具有广泛的生物活性,在抗菌、抗肿瘤、抗结核、抗炎镇痛、酶抑制剂、荧光探针等方面都表现出优异的性能。综述了近年来5-取代-4-氨基-3-巯基-1,2,4-三唑衍生物在医学、农业及材料领域的应用,为今后进一步研究、开发此类化合物提供参考。

Isolation and Characterization of SARS-CoV-2 in Kenya

The discovery of Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) in Wuhan, Hubei province, China, in December 2019 raised global health warnings. Quickly, in 2020, the virus crossed borders and infected individuals across the world, evolving into the COVID-19 pandemic. Notably, early signs of the virus’s existence were observed in various countries before the initial outbreak in Wuhan. As of 12th of April, the respiratory disease had infected over 762 million people worldwide, with over 6.8 million deaths recorded. This has led scientists to focus their efforts on understanding the virus to develop effective means to diagnose, treat, prevent, and control this pandemic. One of the areas of focus is the isolation of this virus, which plays a crucial role in understanding the viral dynamics in the laboratory. In this study, we report the isolation and detection of locally circulating SARS-CoV-2 in Kenya. The isolates were cultured on Vero Cercopithecus cell line (CCL-81) cells, RNA extraction was conducted from the supernatants, and reverse transcriptase-polymerase chain reaction (RT-PCR). Genome sequencing was done to profile the strains phylogenetically and identify novel and previously reported mutations. Vero CCL-81 cells were able to support the growth of SARS-CoV-2 in vitro, and mutations were detected from the two isolates sequenced (001 and 002). Genome sequencing revealed the circulation of two isolates that share a close relationship with the Benin isolate with the D614G common mutation identified along the S protein. These virus isolates will be expanded and made available to the Kenya Ministry of Health and other research institutions to advance SARS-CoV-2 research in Kenya and the region.

液相色谱-串联质谱法测定茶叶及其制品中游离氨基酸的研究进展

本文综述了液相色谱-串联质谱技术在茶叶及其制品中游离氨基酸检测方面的应用,重点讨论了反相色谱和亲水作用色谱分离模式时,低分辨串联质谱和高分辨串联质谱在茶叶及代用茶中游离氨基酸检测的应用,并对其未来发展趋势进行了展望,提出亲水作用色谱分离模式结合串联质谱技术可提高茶叶及其制品中游离氨基酸分析的灵敏度、准确度、选择性和实用性。

SYNTHESIS AND PROPERTIES OF POLYACETYLENES CONTAINING CARBAZOLE AND AMINO ACID MOIETIES

Novel 9-proparylcarbazole monomers containing amino acid moieties,2-N(tert-butoxycarbonyl)-L-alanine- 9-proparylcarbazole ester(1),2-N-(tert-butoxycarbonyl)-L-O-cyclohexyl-L-glutamic acid-9-proparylcarbazole ester(2) and 2-N-(tert-butoxycarbonyl)-L-phenylalanine-9-proparylcarbazole ester(3) were synthesized and polymerized with (nbd)Rh^+[η~6-C_6H_5B^-(C_6H_5)_3]to give the corresponding polymers with number-average molecular weights ranging from 7050 to 10500 in 70%-86%yields.The polymers were completely so...

Assessment of Genetic Relationship and Application of Computational Algorithm to Assess Functionality of Non-Synonymous Substitutions in DQA2 Gene of Cattle, Sheep and Goats

The major histocompatibility complex (MHC) is a fundamental part of the immune system in nearly all vertebrates. DQA2 is a member of the MHC complex and an important candidate gene involved in susceptibility/resistance to various diseases. Therefore, the present study aimed at investigating computationally molecular genetic variation of DQA2 gene of cattle, sheep and goats especially on its evolution and differentiation within and among species as well as the attendant effects of the polymorphism on the function of DQA2 gene. A total of thirty three DQA2 nucleotide sequences comprising cattle (10), sheep (12) and goats (11) were retrieved from the GenBank. Forty seven amino acid substitutions of the wild type alleles located in the putative peptide coding region of caprine DQA2 alleles were obtained from the alignment of deduced amino acid sequences of goats. Out of these, eleven amino acid substitutions (H14L, H14R, L34M, E35L, G56S, G56R, 161V, A62E, D69Q, T72N and T72G) were returned neutral;an indication that they did not impair protein function. The Expected Accuracy (EA) ranged from 53% - 87%. For sheep, sixteen amino acid substitutions (A11P, A11T, A11G, A11M, L14S, L14T, V27L, V27S, G35S, S46T, D55E, L57T, L57A, L57G, K65Q and V68I) appeared beneficial while the rest forty seven appeared harmful (EA ranged from 53% - 93%). Twenty four amino acid substitutions did not impair the function of protein while seventy seven substitutions appeared to have a negative effect on the function of protein of cattle (EA ranged from 53% - 94%). The phylogeny based on nucleotide and amino acid sequences of DQA2 gene revealed the close relatedness of the caprine, ovine and bovine species. The present knowledge would be relevant for performing further genotype-phenotype research as well as pharmacogenetics studies in order to show association between caprine, ovine and bovine DQA2 allelic variation and the clinical progression of infectious diseases especially in a developing country such as Nigeria.

Synthesis of novel fullereneα-amino acid conjugates

Aspartic acid and glutamic acid with protected α-amino and α-carboxyl groups had been used to react with the activated hydroxyl group of N-substituted 3,4-fullero pyrrolidine. The products were deprotected, affording two monofuUerene α-amino acids, monofullerene aspartic acid （mFas） and monofullerene glutamic acid （mFgu）. Then a bifullerene glutamic acid conjugate （bFguC） was synthesized by reaction of mFgu containing protected amino group with N-substituted 3,4-fullero pyrrolidine.

Improvement on the Synthesis of Primary Amino Sugar Derivatives <i>via</i><i>N</i>-Benzyl Intermediates

Primary tosylates 1a-d were converted to the corresponding amino species 3a-d. Benzylamine was proved effective for the substitution of tosylates, using acetonitrile (MeCN) as the solvent of choice and citric acid to remove excess of the reagent from crude products 2a-d. Debenzylation was carried out at circa (ca.) atmospheric pressure of hydrogen gas in the presence of acetic acid (AcOH). The method was also demonstrated in a demo batch experiment for the synthesis of compound 3a on a 50 g scale of 1a.

代用茶茶汤中功能性成分组成及含量分析

该文选取18种代用茶为研究对象,包括蒲公英、桑叶茶、荷叶、黑苦荞、黄金苦荞、全株苦荞、决明子、红枣片、黑枸杞、红枸杞、山楂片、陈皮、茉莉花、胎菊、金盏菊、玫瑰花、金银花和牛蒡根。以游离氨基酸、总酚、总黄酮、游离酚酸、花青素、可溶性糖和多糖为成分考察指标,分析其茶汤中功能性成分的组成和含量,比较水提和醇提对代用茶中总酚、总黄酮和花青素浸出的影响。结果表明:18种代用茶中水浸出物含量为13.1%DW~86.6%DW,其中大部分组成是可溶性糖和多糖,占12.1%~98.0%;游离氨基酸和酚酸分别检出18种和14种,含量较高的氨基酸有精氨酸、天冬酰胺、脯氨酸以及绿原酸类酚酸。玫瑰花的总酚(181.1 mg GAE/g DW)和游离氨基酸总量含量(42.8 mg/g DW)最高;荷叶的总黄酮含量(41.0 mg RE/g DW)最高,金盏菊的多糖含量(6.4%DW)最高,金银花和胎菊中绿原酸类成分含量(54.7、53.7 mg/g DW)较高。2种提取方式的结果表明大部分样品茶汤中总酚、总黄酮和花青素的含量占醇提取物的60%以上。

大黄酰氨基酰胺类衍生物的合成及其抗菌活性

为改善大黄酸的理化性质及抗菌活性,对大黄酸结构进行改造。以大黄酸为原料,苯并三氮唑-N,N,N’,N’-四甲基脲六氟磷酸酯(HBTU)为缩合剂、 N,N-二异丙基乙胺(DIPEA)为催化剂,分别与L-脯氨酸甲酯盐酸盐、L-色氨酸甲酯盐酸盐和L-苯丙氨酸甲酯盐酸盐反应,再加入取代苄胺,合成了6个目标化合物4a~4f。利用核磁共振(~1H NMR、^(13)C NMR、^(19)F NMR)及高分辨质谱对目标化合物结构进行确证和表征,并首次探讨了该类化合物对大肠埃希菌、金黄色葡萄球菌、普通变形杆菌的抑菌活性。研究结果表明:部分目标化合物具有较好的抑菌活性,其中化合物4a对金黄色葡萄球菌的最低抑制质量浓度(MIC)值为0.78 mg/L,化合物4e对普通变形杆菌的MIC值为0.39 mg/L,抑菌活性优于大黄酸,甚至优于对照药物氨苄西林。

外源氨基酸对葡萄产量、生长及品质的影响

为探究氨基酸水溶肥对葡萄产量和品质的影响,以盛果期早黑宝葡萄为试验材料,设置3个处理:常规施肥(CK);增施有机肥(OPT);有机肥+氨基酸水溶肥处理(OPT+AA),研究外源氨基酸对葡萄产量、生长、品质及土壤养分的影响。结果表明,与CK相比,OPT处理葡萄产量降低14.17%,OPT+AA处理葡萄产量降低7.50%,但均不显著。与CK相比,OPT、OPT+AA处理化肥偏生产力均显著增加,OPT+AA处理的N、P_(2)O_(5)、K_(2)O偏生产力分别显著增加73.44%,85.01%,85.01%;OPT+AA处理总糖显著增加8.09%,可溶性固形物显著增加1.32百分点,糖酸比显著增加38.80%,可滴定酸含量显著减少0.16百分点;OPT+AA处理新梢全磷含量显著增加24.73%,全钾含量显著增加24.73%。此外,OPT和OPT+AA处理并不会影响树体生长,且能够有效减少速效养分淋洗、提高植株根域养分含量。综上所述,通过化肥减施并增施有机肥对葡萄产量无显著影响,但可以减少速效养分的淋洗,显著提高化肥偏生产力;在增施有机肥的基础上增施氨基酸水溶肥能够促进树体养分吸收,提高葡萄产量,显著提升果实品质。

4-Hydroxybenzyl-substituted amino acid derivatives from Gastrodia elata

Seven new 4-hydroxyben l-substituted amino acid derivatives (1-7), together with 11 known compounds, were isolated from an aqueous extract of the rhizomes of Go,arodia data Blume. Their structures were determined by spectroscopic and chemical methods. Compounds 1-3 are pyroglutamate derivatives containing 4-hydroxybenzyl units at the N atom and 4-7 are the first examples of natural products with the 4-hydroxybenzyl unit linked vici a thioether bond to 2-hydroxy-3mercaptopropanoic acid (4-6) and 2-hydroxy-4-mercaptobutanoic acid (7), which would be biogenetically derived from cysteine and homocysteine, respectively. The structures of 1 and 2 were verified hi synthesis, while the absolute configurations of 4, 5 and 7 were assigned using Mosher 's method based on the MPA determination rule of A5Rs values. The known compound 4-(hydroxymethy0-5-nifrobenzene1,2-diol (8) exhibited activity against Fe2 r--cysteine induced rat liver microsomal lipid peroxidation with 1050 values of 9.99 x 10 6 mon. (C) 2015 Chinese Pharmaceutical Association and Institute of Materia Medica, Chinese Academy of Medical Sciences. Production and hosting by Elsevier B.'s/. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

猪鸡饲料玉米豆粕减量替代前后能量与氨基酸供需差异的模型分析

能量饲料原料和蛋白饲料原料在典型的猪鸡饲料配方结构中占比分别约为70%和25%,其主要来源于粮食作物。总体上看,我国饲料用粮中谷物的年度产需基本平衡,但玉米长期处于紧平衡状态、大豆高度依赖进口的局面难以缓解,因此,推进谷物供应的结构性调整对于保障粮食安全和稳定畜产品产业链具有重要意义。本文在阐述玉米豆粕减量替代重要意义的基础上,从营养数学模型角度分析测算了玉米豆粕减量替代的可行性,重点分析了减量替代前后能量和氨基酸的供需差异以及原料的供需变化情况,并基于测算结果提出进一步做好玉米豆粕减量替代的对策建议。

Three amino acid substitutions contributing to thermostability of phosphoglucose isomerase in the Glanville fritillary butterfly

Temperature is one of the most important environmental factors that affect organisms,especially ectotherms,due to its effects on protein stability.Understanding the general rules that govern thermostability changes in proteins to adapt high-temperature environments is crucial.Here,we report the amino acid substitutions of phosphoglucose isomerase(PGI)related to thermostability in the Glanville fritillary butterfly(Melitaea cinxia,Lepidoptera:Nymphalidae).The PGI encoded by the most common allele in M.cinxia in the Chinese population(G3-PGI),which is more thermal tolerant,is more stable under heat stress than that in the Finnish population(D1-PGI).There are 5 amino acid substitutions between G3-PGI and D1-PGI.Site-directed mutagenesis revealed that the combination of amino acid substitutions of H35Q,M49T,and I64V may increase PGI thermostability.These substitutions alter the 3D structure to increase the interaction between 2 monomers of PGI.Through molecular dynamics simulations,it was found that the amino acid at site 421 is more stable in G3-PGI,confining the motion of theα-helix 420-441 and stabilizing the interaction between 2 PGI monomers.The strategy for hightemperature adaptation through these 3 amino acid substitutions is also adopted by other butterfly species(Boloria eunomia,Aglais urticae,Colias erate,and Polycaena lua)concurrent with M.cinxia in the Tianshan Mountains of China,i.e.,convergent evolution in butterflies.

Allelic functional variation of FimH among Salmonella enterica subspecies

Salmonella enterica has a wide diversity,with numerous serovars belonging to six different subspecies with dynamic animal-host tropism.The FimH protein is the adhesin mediating binding to various cells,and slight amino acid discrepancy significantly affects the adherence capacities.To date,the general function of FimH variability across dif-ferent subspecies of Salmonella enterica has not been addressed.To investigate the biological functions of FimH among the six Salmonella enterica subspecies,the present study performed several assays to determine biofilm for-mation,Caenorhabditis elegans killing,and intestinal porcine enterocyte cell IPEC-J2 adhesion by using various FimH allele mutants.In general,allelic mutations in both the lectin and pilin domains of FimH could cause changes in bind-ing affnity,such as the N79S mutation.We also observed that the N79S variation in Salmonella Dublin increased the adhesive ability of IPEC-J2 cells.Moreover,a new amino acid substitution,T260M,within the pilin domain in one subspecies llb strain beneficial to binding to cells was highlighted in this study,even though the biofilm-forming and Caenorhabditis elegans-killing abilities exhibited no significant differences in variants.Combined with point muta-tions being a natural tendency due to positive selection in harsh environments,we speculate that allelic variation T26oM probably contributes to pathoadaptive evolution in Salmonella enterica subspecies llb.

Synthesis of New Substituted 4-Amino-3,5-dinitropyridine Derivatives

Facile synthetic routes for the preparation of some new 4-amino-3,5-dinitropyridine derivatives have been revealed. Nitration of 2-chloropyridin-4-amine （1） as a starting material, in an unexpected one-step reaction, to give dinitrated derivatives, followed by nucleophilic substitution reactions with sodium azide, potassium fluoride, ammonia, methylamine, and 4-nitroimidazol, respectively, gave substituted 4-amino-3,5-dinitropyridine derivatives. Meanwhile, its azide derivative underwent a ring closure conversion into 7-amino-6-nitro-[1,2,5]oxadiazolo[3,4-b]- pyridine-1-oxide. It is of significance that all of the nucleophilic substitution reactions were carried out under mild conditions.

A new ureido-substituted amino acid from the tubers of Gymnadenia conopsea

A new ureido-substituted amino acid,conopsamide A（1）,has been isolated from an ethanolic extract of the tubers of Gymnadenia conopsea.Its structure was elucidated by extensive spectroscopic analysis,and the absolute configuration was assigned by Marfey＇s method.The new compound was evaluated for in vitro assay for HDACl（Histone Deacetylase 1） inhibitory activity.

Stereodivergent Benzylic Substitution of Racemic Secondary Benzyl Esters Enabled by Pd/Cu Dual Catalysis

Transition-metal-catalyzed asymmetric benzylic substitution of racemic benzyl esters is an efficient and straightforward route towards the construction of benzylic stereocenters but remains a challenge,due to the difficulty encountered in the suppression ofβ–H elimination and asymmetric induction.Herein,we successfully developed a highly diastereo-and enantioselective benzylic substitution of racemic 1-(aryl)alkyl esters with aldimine esters enabled by Pd/Cu dual catalysis.An array of enantioenrichedα-benzyl substitutedα-amino acids containing vicinal stereocenters were prepared with high levels of diastereo-and enantioselectivities(up to>20:1 dr and>99%ee)and the practicability of the products was further illustrated via their diverse transformations.The dynamic kinetic asymmetric transformation process of the racemic benzyl esters was investigated experimentally and by computational studies.

Tetra-substituted Amino Aluminum Phthalocyanine as a New Red-region Fluorescent Substrate for Horseradish Peroxidase Based Enzyme-linked Immunosorbent Assay

The use of tetra-substituted ammo aluminum phthalocyanine (TAAIPc) as a new red-region fluorescent substrate for horseradish peroxidase (HRP)-based enzyme-linked immunosorbent assay was investigated. TAAIPc displayed an excitation maximum at 610 nm and emission maximum at 678 nm in a strong acidic medium. In the presence of HRP, trace amounts of H2O2 could rapidly and significantly react with TAAIPc, thus quenching the fluorescence of TAAIPc. The Michaelis-Menten parameters Km and Vmax were measured to be 2.82 × 10?6 mol/L?1 and 6.0 × 10?9 mol·L?1, respectively. In this paper, TAAIPc was used in an HRP-based enzyme-linked immunosorbent assay (ELISA) of α-fetoprotein (AFP) in human serum with satisfactory results. AFP could be determined in the concentration range of 0.5–200 ng/mL with a detection limit of 0.2 ng/mL, which was close to that of radioimmunoassay. The advantage of proposed method was strongly minimizing the interference resulting from background fluorescence or scattering light and had a high analytical sensitivity.