固定化大肠杆菌连续生产天门冬氨酸的过程模拟和分析

用卡拉胶包埋大肠杆菌细胞,得到了强度好,活性高的固定化细胞。实验研究了固定化细胞的催化反应速度．扩散-反应模型的计算机分析结果与全混釜反应器实验数据具有相同的规律。列管换热式固定床反应器中的浓度分布可用拟均相一维数学模型描述。从浓度分布和放热量考虑,宜采用串联的填充等量固定化细胞的两只反应器,前者是列管换热式,后者是绝热式。固定化细胞的宏观失活规律可分为三个阶段。开始近似于一级失活,后来保持活力不 变,最后失活较快。     

人心肌胞质天门冬氨酸转氨酶的纯化及性质

从人心肌提纯胞质天门冬氨酸转氨酶同工酶(c-AST)。经匀浆、热处理、硫酸铵分离,进一步用离子交换层析和亲和层析。其比活为220 u/mg。经免疫电泳和PAGE鉴定,达到免疫纯和电泳纯。免疫动物获得较高效价抗体。并对该酶的分子量,等电点和氨基酸组成进行了研究。     

微透析测试刺激皮肤和肌肉神经引起的天门冬氨酸和谷氨酸在脊髓的 …

To investigate the possible mechanisms underlying the difference of NMDA and non-NMDA receptors in spinal nociception originating in skin and muscle, release of aspartate (Asp) and glutamate (Glu) in the spinal dorsal horn was detected by stimulation of cutaneous and muscular nerves in cats using microdialysis technique. Asp and Glu were increased respectively by (323 +/- 55)% and (169 +/- 16)% following stimulation of cutaneous nerve, but by (150 +/- 16)% and (218 +/- 42)% respectively following stimulation of muscular nerve. Asp increase was approximately three times higher than that of Glu following cutaneous nerve-stimulation (P < 0.01), while Glu increase was approximately twice as high as that of Asp following muscular nerve-stimulation (P < 0.05). It is likely that nociceptive cutaneous and muscular inputs preferentially elicite release of Asp and Glu respectively, resulting in a functional differentiation of NMDA and non-NMDA receptor in the mediation of different nociceptive information.     

有机酸和氨基酸行业循环经济模式的思考与实践——富马酸和L-天门冬氨酸清洁生产

一 背景 有机酸与氨基酸是生物化工产业的重要组成部分,富马酸、L- 天门冬氨酸分别是其中的代表性产品.富马酸是一种重要的有机化工原料和精细化工产品,广泛用于化工、涂料、树脂、增塑剂等行业,目前越来越多用作生产氨基酸(L- 天门冬氨酸) 的原料以及新型环保型水处理剂的原料.     

微透析测试刺激皮肤和肌肉神经引起的天门冬氨酸和谷氨酸在脊髓的释放

为分析ＮＭＤＡ和非ＮＭＤＡ受体在介导脊髓不同性质疼痛的机能分化,应用微透析技术,测量刺激皮肤和肌肉神经引起的天门冬氨酸（Ａｓｐ）和谷氨酸（Ｇｌｕ）在脊髓背角的释放。电刺激皮肤神经兴奋Ｃ纤维诱发的Ａｓｐ和Ｇｌｕ的释放分别是基础值的（３２３±５５）％（Ｐ＜００１）和（１６９±１６）％（Ｐ＜００５）;电刺激肌肉神经兴奋Ｃ纤维诱发的Ａｓｐ和Ｇｌｕ的释放分别是基础值的（１５０±１６）％（Ｐ＜００１）和（２１８±４２）％（Ｐ＜００５）。兴奋皮肤传入引起的Ａｓｐ释放明显高于Ｇｌｕ的释放（约３倍）;而兴奋肌肉传入引起的Ｇｌｕ释放明显高于Ａｓｐ的释放（约２倍）。从而提示,皮肤伤害性传入主要引起Ａｓｐ的释放增加,而肌肉的伤害性传入则主要引起Ｇｌｕ的释放增加,它们分别主要作用于ＮＭＤＡ和非ＮＭＤＡ受体而介导不同的痛传入信息。     

聚天门冬氨酸和壳聚糖复配剂对谷子光合特性、氮素利用率及产量的影响

为探究全基施背景下聚天门冬氨酸和壳聚糖复配剂(polyaspartic acid-chitosan, PAC)对东北春谷光合特性、氮肥利用效率及产量的调控效应,本研究以“张杂谷13号”和“华优谷9号”为材料,于2020年和2021年在中国农业科学院作物科学研究所公主岭试验站开展裂区试验,以PAC为主区处理,不同氮肥施用量为副区处理,共设置0、75、112.5、150、225和337.5 kg·hm^-2 6个氮肥水平。结果表明：相同施氮量下,与常规氮肥处理相比,PAC配施氮肥处理显著提高了2个谷子品种氮肥表观利用率,增大了叶面积指数和花后旗叶SPAD值,显著提高花期及灌浆中期旗叶净光合速率、蒸腾速率和气孔导度,降低旗叶胞间CO₂浓度,促进干物质积累,提高产量;张杂谷13号在2020年和2021年的产量增幅分别为11.24%～21.55%和8.65%～14.22%,华优谷9号两年的产量增幅分别为5.53%～15.75%和10.43%～16.17%;PAC有效缓解了全基施施肥方式造成的谷子生育后期脱氮早衰,减少了由于氮肥利用效率低下造成的氮素流失;...     

脂肪酶催化合成生物柴油的研究进展

环保型燃料生物柴油有望解决能源短缺的问题,脂肪酶催化动植物油脂合成生物柴油的方法具有反应条件温和、产物易分离和不污染环境等优点。综述了酶催化法在提高脂肪酸酯产率和减少生产成本等方面的研究进展。     

邻甲苯甲酸催化合成邻甲苯腈的研究

采用连续流动塔式气固催化法合成邻甲苯腈,通过正交实验得出最佳反应条件为:反应温度270℃,反应物摩尔比n_(邻甲苯甲酸):n_(氨气)=1:1.6。由于主要反应物为固体,在实验室采取间歇投料小规模实验,单次投料量为5g(投料间隔时间为30min),最高的摩尔产率为99.3%。     

酶解大豆蛋白产天冬氨酸蛋白酶抑制剂的研究

本文通过采用可控酶解的方式酶解大豆蛋白获得了一种源自大豆的天冬氨酸蛋白酶抑制剂SAPI( soy aspartic proteinase inhibitor).酶解液经过DEAE-52阴离子交换层析、Superdex Peptide 10/300 GL凝胶层析、SOURCE 15RPC反相层析分离后最终比抑制活力为254.2 IU/mg,纯化倍数为62.SAPI对胃蛋白酶(3000U)半数抑制浓度IC50为25.67 μg/mL,有良好的热稳定性,属于一种非竞争性抑制剂.     

Chemical Modification of Aspartic Acid and Arginine Residues in Horseradish Peroxidase Role of ASP 43 and ARG 38 in the Catalytic Cycle

In an attempt to alter the catalytic properties of horseradish peroxidase (HRP, EC 1.11.1.7), aspartic, glutamic and arginine residues were modified using ethanedithiol and diacetyl. Modification of Asp and Glu led to a marked increase in V_max along with denaturation of the protein. The thiol groups introduced were thought to be responsible, despite being situated on the periphery of the molecule as shown by the modification of the apoenzyme. The role of Arg 38 in the activation of hydrogen peroxide was indicated by the modifications of both enzyme and apoenzyme. An amino acid residue close to Arg 38 was thought to take over its function after blocking the group.     

Propagation of Biochirality: Crossovers and Nonclassical Crystallization Kinetics of Aspartic Acid in Water

All experimental procedures discussed could be treated as a screening tool for probing the existence of molecular association among the chiral molecules and the solvent system. The molecular association phases of a racemic conglomerate solution (CS) and a racemic compound solution (RCS), and the templating effect of aspartic acid solid surface were observed to minimize the chance of redissolving racemic conglomerate and racemic compound aspartic acid in water and reforming an RCS in crossovers experiments. Only 1 %wt% of l‐aspartic acid was adequate enough to induce a transformation from a racemic compound aspartic acid to a racemic conglomerate aspartic acid. This would make the propagation of biochirality more feasible and sound. However, tetrapeptide, (l‐aspartic acid)₄, failed to induce enantioseparation as templates purely by crystallization. Nonclassical crystallization theory was needed to take into account the existence of a CS. Fundamental parameters of the crystallization kinetics such as the induction time, interfacial energy, Gibbs energetic barrier, nucleation rate, and critical size of stable nuclei of: (i) racemic compound aspartic acid, (ii) racemic compound aspartic acid seeded with 1 %wt% l‐aspartic acid, (iii) racemic conglomerate aspartic acid, and (iv) l‐aspartic acid were evaluated and compared with different initial supersaturation ratios. Morphological studies of crystals grown from the crystallization kinetics were also carried out.Chirality 25:768–779, 2013. © 2013 Wiley Periodicals, Inc.     

氨基酸转运载体研究进展

氨基酸转运载体是介导氨基酸跨膜转运的膜蛋白,在氨基酸营养机体细胞和神经调节过程中起着重要作用;而且,其功能异常会导致严重的氨基酸吸收和代谢障碍性疾病,也具有重要的病理学意义。本文就近年来关于中性氨基酸、酸性氨基酸和碱性氨基酸转运载体家族成员及其组织分布、分子生物学特征、生理功能和病理学意义等研究进展进行了综述。     

生物技术生产丁酸的研究进展

丁酸作为一种重要的化工原料,已经广泛应用于食品添加剂与医药等领域。目前,工业上生产丁酸主要是从石油中提取有机化合物进行化学合成。与有机化合物合成法相比,微生物发酵产丁酸的优势有：所用的原料来源非常广,发酵过程低能耗,不污染环境,而且可以持续添加原料发酵生产丁酸。因此,通过生物技术发酵生产丁酸越来越受到人们的重视。介绍了丁酸的性质、产丁酸菌株的特点、微生物发酵产丁酸的细胞代谢途径及其调控、发酵法生产丁酸的工艺运行方式和产丁酸菌株及其代谢产物的生理功能这五部分内容,以期为今后开展发酵法产丁酸的微生物基因工程改造以及生产工艺的优化提供参考。     

植物天冬氨酸代谢途径关键酶基因研究进展

谷类作物和豆类作物的营养价值主要体现在以天冬氨酸为前体的必需氨基酸的含量上。植物中这些氨基酸的含量受天冬氨酸代谢途径中关键酶基因的影响。本文综述了这些酶基因的克隆、在大肠杆菌和不同植物中表达的研究进展。     

A New Pathway to Aspartic Acid from Urea and Maleic Acid Affected by Ultraviolet Light

The photochemistry of a mixture of ureaand maleic acid, which are thought to have been widelypresent on the primitive Earth, was studied in order toexamine a possibility of the formation of amino acids. When an aqueous solution of urea and maleic acid wasirradiated with an ultraviolet light of wavelength 172 nm,urea was revealed to be rather resistant to photochemicaldecomposition. In contrast, maleic acid was completelydecomposed within 4 h, reflecting the reactivity of a C-Cdouble bond in the molecule. In the reaction mixture, 2-isoureidosuccinic acid was detected. The acid wasconsidered to be formed by addition of an isoureido radicalwhich had been produced from urea by the action of ahydroxyl radical, to a C-C double bond of maleic acid. Theisoureido group of the product was revealed to undergothermal rearrangement to afford 2-ureidosuccinic acid (N-carbamoylaspartic acid). The result suggested a novelpathway leading to the formation of aspartic acid from non-amino acid precursors, possibly effected by UV-light on theprimitive Earth. The formation of ureidocarboxylic acidsis of another significance, since they are capable ofundergoing thermal polymerization, resulting in formationof polyamino acids.     

脱落酸衍生物及其类似物研究进展

脱落酸是一种广泛存在于植物体内的植物激素,它与植物离层形成、诱导休眠、抑制发芽、促进器官衰老和脱落及增强抗逆性等密切相关.本文就其衍生物及类似物的研究做一概要综述,并对脱落酸的衍生化及结构改造与生物活性关系做了综合评价,从目前的情况来看,对8'或9'位甲基的衍生化是相对比较成功的,其中出现了一些活性较高的化合物,这也是近年来ABA衍生化研究的热点.