A fast method for predicting amino acid mutations that lead to unfolding

Amino acid mutation(s) that cause(s) partial or total unfoldingof a protein can lead to disease states and failure to producemutants. It is therefore very useful to be able to predict whichmutations can retain the conformation of a wild-type proteinand which mutations will lead to local or global unfolding ofthe protein. We have developed a fast and reasonably accuratemethod based on a backbone-dependent side-chain rotamer libraryto predict the (folded or unfolded) conformation of a proteinupon mutation. This method has been tested on proteins whosewild-type 3D structures are known and whose mutant conformationshave been experimentally characterized to be folded or unfolded.Furthermore, for the cases studied here, the predicted partiallyfolded or denatured mutant conformation correlate with a decreasein the stability of the mutant relative to the wild-type protein.The key advantage of our method is that it is very fast andpredicts locally or globally unfolded states fairly accurately.Hence, it may prove to be useful in designing site-directedmutagenesis, X-ray crystallography and drug design experimentsas well as in free energy simulations by helping to ascertainwhether a mutation will alter or retain the wild-type conformation.     

Preparation of polymer-supported amino acid

Summary Insoluble polymer-supported amino acids have been synthesized by simple one-pot synthesis. Amino acids were solubilized in organic solvent by trimethylsilylation. Solubilized amino acids (L-Tyr, L-Ser, D-HPG, L-Cys) having functional groups such as OH or SH were easily attached to crosslinked polystyrene beads through benzyl ether or thioether linkage. Other amino acids without extra functional groups could be attached to the polymer through benzyl amine linkage.     

氨基磺酸的清洗技术

介绍了氨基磺酸的性能和清洗机理,并例举了采用氨基磺酸清洗塑胶机冷却水系统污垢的清洗工艺,清洗效果显著.     

N-叔丁氧羰基-L-丙氨酸的合成研究

以二碳酸二叔丁酯和氨基酸为原料,在碱性条件下反应合成标题化合物,产物经红外光谱、核磁光谱和质谱确认.研究了不同碱和溶剂对反应的影响.     

一种N-酰基氨基酸表面活性剂的合成研究

以4-溴丁酸乙酯和对特辛基苯酚为原料进行Williamson反应,然后进行酯的水解、酸化制备羧酸,再用制得的羧酸和二氯亚砜反应制备酰氯,最后与甘氨酸钾通过Schotten-Baumann缩合反应来制备N-酰基氨基酸表面活性剂。通过红外光谱和质谱等对所合成的化合物进行了结构表征。对Williamson反应、酰化反应及Schotten-Baumann缩合反应的工艺条件进行了优化,得出各步反应的较优条件。醚化反应:反应时间5 h,n(对特辛基苯酚)∶n(4-溴丁酸乙酯)=1∶1.4,反应温度78℃左右,以DMF为溶剂;酰化反应:二氯亚砜作为酰化试剂;Schotten-Baumann缩合反应:反应时间5 h,n(甘氨酸)∶n(酰氯)=2∶1,反应温度0℃左右,pH=9～10。在此条件下,N-酰基氨基酸表面活性剂的收率为68%。     

氨基磺酸及其混合酸腐蚀性比较

通过对氨基磺酸及与一定量的盐酸混合酸,在投加同剂量的缓蚀剂后对铁、铜、不锈钢金属腐蚀率大小的实验比较,得出在氨基磺酸溶液中加入一定量的盐酸和缓蚀剂可以减轻其对铁、铜、不锈钢的腐蚀性,又可以增加其反应速度.     

单体酸的理化性能及组成的GC/MS分析

研究棉籽油酸生产二聚酸的副产物——单体酸的组成及性质,测定了单体酸的碘值、酸值、皂化值等理化指标。结果表明,样品是一种含有较长碳链、不易发生酸败的脂肪酸混合物。样品用甲醇进行甲酯化,用GC/MS进行分析和鉴定,共鉴定出棕榈酸(12.16%)、肉豆蔻酸(6.70%)、十八烯酸(25.61%)、硬脂酸(33.77%)等16种物质。     

Synthesis of amino acid derivatives of ethanolamine

Summary N-Phthaloylglycylaminocthanol may be prepared in 24% yield by a modification of the Shechan carbodiimide synthesis of peptides of hydroxy amino acids (6). The amino alcohol is characterized as to melting point, solubility in various solvents, the ability to form a derivative with acetic anhydride, percentage of nitrogen, and infrared spectra. In acid solution this compound appears to undergo the aminoacyl shift characteristic of compounds containing an amide linkage and a free hydroxyl group. Attempts to isolated N-glycylaminoethanol by hydrolysis of the phthaloyl derivative with hydrazine hydrate have been unsuccessful. Impure N-phthaloylalanylaminoethanol and N-phthaloylglycylglycylaminoethanol were also synthesized by means of this procedure. Several other methods for synthesizing N-glycylaminoethanol are discussed. Portion of a thesis presented by Elizabeth C. Smith as partial fulfillment of the requirements for the degree of Doctor of Philosophy. Authorized for publication as Paper No. 2399 on Sept. 1, 1959, in the Journal Series of the Pennsylvania Agricultural Experiment Station.     

Designing amino acid residues with single-conformations

Drug design can benefit from the use of non-coded amino acids, such as alpha-amino isobutyric acids (Aib) or sarcosine (N-methyl-glycine). Non-coded amino acids can confer resistance to enzymatic degradation and increase the conformational stability of the peptides. We have simulated the conformational effects of combining N-methylation, bulky groups on the Calpha atom and/or thioamides using the class II CFF91 force field and our thioamide force field parameters. Although single amino acid substitutions (e.g. Aib) can restrict the available conformations, they do not necessarily lead to unique conformers, however, we predict that some of the amino acids described in this report will fold to a single phi, psi conformation (e.g. N-methylated and thioamide penicillamine). Several other amino acid/thiopeptide combinations were designed, which are predicted to prefer only two conformations. Novel amino acids of this type should prove useful for designing peptides with defined conformations.     

氨基酸废水的回收利用及处理

采用浓缩回收 －生物处理的方法对氨基酸废水进行处理,出水水质达到了国家排放标准,有较好的经济效益和社会效益。     

氨基酸检测方法的进展和现状

氨基酸是构成蛋白质的基础结构,是生物体内不可缺少的营养成分,几乎与一切生命活动相关。氨基酸的准确测量,在氨基酸生产的质量控制、临床疾病诊断、饲料的品质评价等领域具有重要意义。许多国内外研究机构都在研究快速、准确的检测方法。常见的检测方法有离子交换色谱法、气相色谱法、高效液相色谱法、毛细管电泳、色谱质谱联用等。比较全面地总结了氨基酸的检测方法及其研究进展。     

药用氨基酸复合盐的合成研究

氨基酸复合盐是一类具有独特药学作用的氨基酸衍生物.以氨基酸单体为原料研究了L-鸟氨酸L-天冬氨酸盐、L-精氨酸L-谷氨酸盐、L-精氨酸L-焦谷氨酸、L-赖氨酸L-谷氨酸盐等7种氨基酸复合盐的合成方法、结晶条件.产品的转化率均在80%以上,质量符合AJI97等相关标准,工艺适合工业化生产.     

Adsorption of amino acid derivatives on calixarene carboxylic acid impregnated resins

Macrocyclic host molecules calixarene carboxylic acid derivatives are found to act as powerful extractants for biologically important amino compounds. A series of adsorbents were prepared from a methacrylate-based polymer Amberlite XAD-7 by impregnation with various calixarene derivatives, for adsorptive recovery of amino acid derivatives. The larger macrocycles calix[6]arene and calix[8]arene carboxylic acid derivatives were more effective for adsorption of amino acid derivatives on the impregnated resin than the calix[4]arene derivative. Since adsorption proceeds mainly via electrostatic interaction, the carboxylic acid groups introduced into the calixarene platform were important for adsorption of cationic amino acid derivatives. The adsorption selectivity for amino compounds using adsorbent impregnated with the calix[6]arene carboxylic acid derivative depends simply on the hydrophobicity of the adsorbates.     

Physicochemical characteristics of waste sea shells for acid gas cleaning absorbent

The properties of waste shells, which cause pollution problems, are investigated in Southern beach, Korea. The absorbent surface area was affected by the contaminant gas removal efficiency of the waste shell absorbents, pore structures, absorbent deliquescence and hygroscopicity during the contaminant gas reaction. The BET surface area of calcination/hydration waste shell and limestone samples was increased by hydration in isothermal conditions. The absorption rate with acid gas is predicted by apparatus for measuring the hydration rate. The BET surface area of waste shell samples hydrated at 90 ‡C isothermal condition was greatly increased. And pore size distribution and diameter were increased after calcination/hydration reaction. Waste seashells can be regarded as a good absorbent for removing acid gases. Therefore, the recycling of waste seashells as a substitute for limestone would be profitable. Key words:Waste Shell, Absorbent, Hydration Rate, Flue Gas Desulfurization This paper was presented at The 5th International Symposium on Separation Technology-Korea and Japan held at Seoul between August 19 and 21, 1999.     

Concurrent mutations in six amino acids in beta-glucuronidase improve its thermostability

To achieve a thermostable beta-glucuronidase (GUS) and identify key mutation sites, we applied in vitro directed evolution strategy through DNA shuffling and obtained a highly thermostable mutant GUS gene, gus-tr, after four rounds of DNA shuffling and screening. This variant had mutations in 15 nucleic acid sites, resulting in changes in 12 amino acids (AAs). Using gus-tr as the template, we further performed site-directed mutagenesis to reverse the individual mutation to the wild-type protein. We found that six sites (Q493R, T509A, M532T, N550S, G559S and N566S) present in GUS-TR3337, were the key AAs needed to confer its high thermostability. Of these, Q493R and T509A were not reported previously as important residues for thermostability of GUS. Furthermore, all of these six mutations must be present concurrently to confer the high thermostability. We expressed the gus-tr3337 gene and purified the GUS-TR3337 protein that contained the six AA mutations. Compared with the wild-type protein which lost its activity completely after 10 min at 70 degrees C, the mutant GUS-TR3337 protein retained 75% of its activity when heated at 80 degrees C for 10 min. The GUS-TR3337 exhibited high activity even heated at 100 degrees C for 30 min on nitrocellulose filter. The comparison of molecular models of the mutated and wild-type enzyme revealed the relation of protein function and these structural modifications.     

黄腐酸分级及结构研究

简述了黄腐酸的性质和应用,介绍了国内外黄腐酸的分级方法研究进展,并对各种分级方法的优缺点进行比较。分析了凝胶、透析和超滤等现代技术在黄腐酸分级中的应用,归纳总结了黄腐酸分级后活性组分在各级分中分布特征,最后对分级与分离技术发展前景进行展望。     

黄腐酸分级及结构研究

简述了黄腐酸的性质和应用,介绍了国内外黄腐酸的分级方法研究进展,并对各种分级方法的优缺点进行比较。分析了凝胶、透析和超滤等现代技术在黄腐酸分级中的应用,归纳总结了黄腐酸分级后活性组分在各级分中分布特征,最后对分级与分离技术发展前景进行展望。     

Surface imprinted polymers recognizing amino acid chirality

A highly enantioselective polymer was prepared for the separation of optically active tryptophan methylester by a surface molecular imprinting technique. An organophosphorus compound was found to be effective as a functional host molecule for recognizing the chirality of the amino acid ester. The imprinted polymers exhibited a higher template effect toward the corresponding imprinted tryptophan methylester than its isomer and analogues, while a reference polymer prepared without an imprinting molecule did not show any selectivity toward the enantiomers. The enantioselective recognition was quantitatively evaluated by determination of the binding constants of the D ‐ and L ‐tryptophan methylester to the imprinted polymers. Furthermore, the mechanism for producing enantioselectivity was deduced from FTIR and ¹H‐NMR spectra. Based on the results obtained we concluded that the enantiomeric selectivity was mainly caused by electrostatic and hydrogen bonding interactions between the functional organophosphorus molecule and the target tryptophan methylester on the polymer surface. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 695–703, 2000     

氨基酸金属有机框架的研究进展

氨基酸金属有机框架是指含有氨基酸单元的有机配体与金属离子共同参与合成的具有周期性结构的材料。氨基酸作为蛋白质的组成成分,具有绿色环保、生物相容性良好、种类多样、价格低廉等优点,将其引入金属有机框架（MOFs）可以赋予材料特殊的柔性结构、丰富的活性位点、优良的应用性能等特征。该文综述了氨基酸MOFs的结构维度分类,介绍了氨基酸MOFs的主要合成方式,包括溶剂热法、机械化学合成法、微波加热辅助法,进一步阐述了材料的性能调控,重点介绍了这类材料在手性拆分、催化、吸附等领域的应用。最后,通过分析当前氨基酸金属有机框架材料存在的稳定性不好、结构难以预测等问题,对其未来在生物医药领域的研究重点进行了展望。