从RNA酶解液中分离5'-尿苷酸

采用2根强酸性阳离子交换柱、1根弱碱性阴离子交换柱和1根强碱性阴离子交换柱进行4柱串联,可以从RNA酶解液中分离得到5'-尿苷酸,而不混有其它核苷酸,并对离子交换树脂种类、树脂量、洗脱剂等作了进一步研究.结果表明,采用4柱串联分离5'-尿苷酸,其总收率达到92.1％、结晶纯度达到86％以上.     

从RNA酶解液中分离5-尿苷酸

采用2根强酸性阳离子交换柱、1根弱碱性阴离子交换柱和1根强碱性阴离子交换柱进行4柱串联,可以从RNA酶解液中分离得到5-尿苷酸,而不混有其它核苷酸,并对离子交换树脂种类、树脂量、洗脱剂等作了进一步研究。结果表明,采用4柱串联分离5-尿苷酸,其总收率达到92．1％、结晶纯度达到86％以上。     

乙醇-水溶剂中5'-尿苷酸二钠溶解度测定与关联

采用内置双光路激光检测器,在293.2-318.2 K温度范围内,测定了5'-尿苷酸二钠在纯水及不同乙醇-水混合溶剂中的溶解度.分别用R-K方程、λh方程和Wilson方程3种溶解度模型,采用最小二乘法关联实验数据,并对比不同溶解度模型.结果表明,在乙醇质量分数为0-0.65区间内,5'-尿苷酸二钠溶解度随着温度的升高而增大,随乙醇质量分数的增大而显著减小,λh方程对5'-尿苷酸二钠溶解度关联效果最好.将λ,h表达为乙醇质量分数的函数,并用于内插计算,精度满足工程要求.     

乙醇-水溶剂中5′-尿苷酸二钠溶解度测定与关联

采用内置双光路激光检测器,在293.2—318.2 K温度范围内,测定了5′-尿苷酸二钠在纯水及不同乙醇-水混合溶剂中的溶解度。分别用R-K方程、λh方程和Wilson方程3种溶解度模型,采用最小二乘法关联实验数据,并对比不同溶解度模型。结果表明,在乙醇质量分数为0—0.65区间内,5′-尿苷酸二钠溶解度随着温度的升高而增大,随乙醇质量分数的增大而显著减小,λh方程对5′-尿苷酸二钠溶解度关联效果最好。将λ,h表达为乙醇质量分数的函数,并用于内插计算,精度满足工程要求。     

乙醇-水混合溶剂中5′-尿苷酸二钠的结晶介稳区

采用双光路激光法,在293.2～318.2 K温度范围内,研究了5′-尿苷酸二钠在不同比例乙醇-水混合溶剂中的溶解与超溶解特性,得到了5′-尿苷酸二钠的结晶介稳区。采用λh方程关联了4个体系的溶解度数据,进而分别求得各体系下的混合焓和结晶焓。同时,探讨了搅拌转速、pH值和钠离子浓度对结晶介稳区的影响。实验结果表明,与温度相比较,乙醇质量分数是影响溶解度和超溶解度的主要因素;随乙醇质量分数的增大,5′-尿苷酸二钠的溶解度和超溶解度显著减小;在相同条件下,溶液pH值和钠离子浓度的升高,以及搅拌转速的降低均会增大5′-尿苷酸二钠结晶介稳区的宽度。     

5'-鸟苷酸的晶体结构预测

采用Cerius2软件中的Polymorph模块,预测5'-鸟苷酸的晶体结构.采用蒙特卡罗模拟退火方法在晶格能超曲面上搜索晶体可能的堆垛方式;基于堆垛相似性,有选择性的将这些可能的结构划分成各个特征组;在所有自由度上对每一特征结构进行优化;对优化后的各个结构再次分组排除重复;根据晶格能对最后得到的结构进行排序,得到5'-鸟苷酸最可能的空间群为P212121.     

从酶转化液中分离提取L-苯丙氨酸的工艺研究

利用JK006阳离子交换树脂从酶转化液中分离提取L-苯丙氨酸,对吸附、除杂、洗脱再生等工艺进行研究。吸附损失率几乎为零,对L-苯丙氨酸的吸附量达到97.5g.kg-1湿树脂,L-苯丙氨酸洗脱收率达到94.5%,洗脱液浓度达到28~30g.L-,并对洗脱尾流和再生洗涤水进行了再利用,降低了成本,减少了污染。     

1-(5'-溴阿魏酰基)4-(2'-氯)苄基哌嗪盐酸盐的合成及表征

以5'-溴阿魏酸为原料,通过酚羟基的乙酰化保护、羧酸羟基氯代、酰化、脱乙酰基、成盐,制备出的标题化合物为新化合物,未见文献报道,其结构经IR、1HNMR、MS及元素分析确证.     

5'-硝基水杨基荧光酮-溴化十六烷基三甲胺-柠檬酸光度法测定锌

研究了5'-硝基水杨基荧光酮(5'-NSAF)-溴化十六烷基三甲胺(CTMAB)-柠檬酸与锌形成配合物的显色反应条件和光度性,建立了光度法测定锌的新方法。结果表明,在p H 9.5 Na2B4O7-Na OH的缓冲溶液中,锌与5'-硝基水杨基荧光酮-CTMAB-柠檬酸能生成稳定的配合物,其最大波长在570 nm,锌的含量在0~0.5μg/m L范围内服从比耳定律,表观摩尔吸光系数为1.2×105L/(mol·cm)。此方法用于葡萄糖酸锌片样品中锌的测定,回收率为101%~104%,RSD为1.5%~3.4%(n=5)。     

反-4-(5'-丙基-四氢吡喃-2'-基)-环己基甲酸的合成

以反-4-(5'-丙基-四氢吡喃-2'-基)-苯甲酸(3PyPA)为原料,经催化加氢合成顺/反-4-(5'-丙基-四氢吡喃-2'-基)-环己基甲酸(3PyHA)混合物。加氢条件实验表明,以Ru/C为催化剂,以NaOH水溶液为反应介质,当反应温度为75～85℃,压力为3.5 MPa时反应效果最佳。加氢完粗品经高温异构化反应,甲苯乙醇混合溶剂重结晶得色谱纯度99.5%以上的反-3PyHA。     

Enzymatic Redox Cascade for One‐Pot Synthesis of Uridine 5′‐Diphosphate Xylose from Uridine 5′‐Diphosphate Glucose

Synthetic ways towards uridine 5′‐diphosphate (UDP)‐xylose are scarce and not well established, although this compound plays an important role in the glycobiology of various organisms and cell types. We show here how UDP‐glucose 6‐dehydrogenase (hUGDH) and UDP‐xylose synthase 1 (hUXS) from Homo sapiens can be used for the efficient production of pure UDP‐α‐xylose from UDP‐glucose. In a mimic of the natural biosynthetic route, UDP‐glucose is converted to UDP‐glucuronic acid by hUGDH, followed by subsequent formation of UDP‐xylose by hUXS. The nicotinamide adenine dinucleotide (NAD⁺) required in the hUGDH reaction is continuously regenerated in a three‐step chemo‐enzymatic cascade. In the first step, reduced NAD⁺ (NADH) is recycled by xylose reductase from Candida tenuis via reduction of 9,10‐phenanthrenequinone (PQ). Radical chemical re‐oxidation of this mediator in the second step reduces molecular oxygen to hydrogen peroxide (H₂O₂) that is cleaved by bovine liver catalase in the last step. A comprehensive analysis of the coupled chemo‐enzymatic reactions revealed pronounced inhibition of hUGDH by NADH and UDP‐xylose as well as an adequate oxygen supply for PQ re‐oxidation as major bottlenecks of effective performance of the overall multi‐step reaction system. Net oxidation of UDP‐glucose to UDP‐xylose by hydrogen peroxide (H₂O₂) could thus be achieved when using an in situ oxygen supply through periodic external feed of H₂O₂ during the reaction. Engineering of the interrelated reaction parameters finally enabled production of 19.5 mM (10.5 g L ⁻¹) UDP‐α‐xylose. After two‐step chromatographic purification the compound was obtained in high purity (>98%) and good overall yield (46%). The results provide a strong case for application of multi‐step redox cascades in the synthesis of nucleotide sugar products.

     

Selective Separation of Mono Glyceryl Ferulate Using Water from an Ionic Liquid Solution of Enzymatic Transesterification

Mono glyceryl ferulate (MFG), an all-natural derivative of ferulic acid, can be used as antioxidant and a UV filter in food and cosmetic formulations. However, the applications of MFG in these fields are limited due to its low availability in nature. In this work, a novel method for selective separation of MFG from a room temperature ionic liquid (RTIL) solution of enzymatic transesterification of ethyl ferulate with glycerol was investigated. The effects of different extractants and extraction conditions on the selective separation of MFG were also studied. High extraction yields of MFG (98.23 ± 1.09 %) and the relative content of MFG in the extracts (97.76 ± 1.25 %) were achieved using neutral deionized water as extractant under the following conditions: 0.5:1 volume ratio of water to RTIL solution, extraction time of 6 min, centrifugation time of 6 min, and extraction done eight times. The extraction thermodynamics showed that the extraction of MFG was an exothermic process. The purified MFG exhibited good UV adsorbing properties at 280–360 nm with a λ _max at 322 nm.     

酶法降解壳聚糖工艺研究

采用非专一性酶(溶菌酶、纤维素酶)和专一性酶(壳聚糖酶)降解壳聚糖,探讨了不同条件对壳聚糖降解的影响.结果表明,溶菌酶降解壳聚糖的最佳条件为反应时间3.0 h、反应温度50℃、pH值4.0、酶用量40 U·mL-1;纤维素酶降解壳聚糖的最佳条件为反应时间1.5 h、反应温度55℃、pH值5.5、酶用量40 U·mL-1;壳聚糖酶降解壳聚糖的最佳条件为反应时间2.0 h、反应温度45℃、pH值5.0、酶用量30 U·mL-1.对壳聚糖酶酶解产物进行HPLC分析,发现得到了分子量分布较窄的壳寡糖.     

Separation of Alcohols from Solution by Lignin Gels

Abstract

Partition relationships of radioisotope labeled ethanol and 1-butanol between aqueous solutions and a hydrated commercial Kraft softwood lignin gel are presented. These initial evaluations indicate that lignin hydrogels preferentially concentrate 1-butanol and, to a lesser extent, ethanol. The process implications and potential use of lignin as an inexpensive extractant are discussed.     

Enzymatic RNA Production from NTPs Synthesized from Nucleosides and Trimetaphosphate**

A mechanism of nucleoside triphosphorylation would have been critical in an evolving “RNA world” to provide high-energy substrates for reactions such as RNA polymerization. However, synthetic approaches to produce ribonucleoside triphosphates (rNTPs) have suffered from conditions such as high temperatures or high pH that lead to increased RNA degradation, as well as substrate production that cannot sustain replication. Previous reports have demonstrated that cyclic trimetaphosphate (cTmp) can react with nucleosides to form rNTPs under prebiotically-relevant conditions, but their reaction rates were unknown and the influence of reaction conditions not well-characterized. Here we established a sensitive assay that allowed for the determination of second-order rate constants for all four rNTPs, ranging from 1.7×10⁻⁶ to 6.5×10⁻⁶ M⁻¹ s⁻¹. The ATP reaction shows a linear dependence on pH and Mg²⁺, and an enthalpy of activation of 88±4 kJ/mol. At millimolar nucleoside and cTmp concentrations, the rNTP production rate is sufficient to facilitate RNA synthesis by both T7 RNA polymerase and a polymerase ribozyme. We suggest that the optimized reaction of cTmp with nucleosides may provide a viable connection between prebiotic nucleotide synthesis and RNA replication.     

Separation of Gallium and Aluminum from HCl Solution by Microemulsion

Gallium was separated from aluminum in hydrochloric acid medium by a steady microemulsion. In the cetyltrimethylammonium bromide (CTAB)/n-pentanol/n-heptane/HCl/tributyl phosphate (TBP) system, TBP was introduced as the modifier to avoid emulsification of the microemulsion. The extraction efficiency on gallium was also improved by adding TBP. The factors that influenced the separation efficiency were explored. The results of the experiments showed that the gallium and aluminum were effectively separated within a very short time, and the extraction efficiencies of gallium and aluminum were 92% and 5%, respectively. The maximum back-extraction efficiency of gallium was 92% in HCl solution (4 M).     

钢渣中二价金属氧化物固溶体的选别性研究

为了解决钢渣活性低、在水泥生产中难以利用的问题,探索分选出RO相(二价金属氧化物固溶体)惰性矿物的可能性。测定两种钢渣的岩相特征,探明RO相及伴生矿物的力学性质、比磁化率和比电阻,并通过分选钢渣粉料实验进行验证。结果表明：钢渣中RO相含量为20%～30%,平均粒径为31～45μm; RO相是钢渣中密度、硬度最大的矿物,在粗粒级和重组分中富集,气力分选粗粉中RO相含量是细粉的2.3倍;RO相属于中磁性矿物,伴生矿物属于非磁性矿物,在中等磁场磁选中能分选回收;伴生矿物为非导体矿物,RO相为导体矿物或中等导体矿物能用电选回收。RO相中FeO/MgO的摩尔比越高对三种分选越有利;氧化焙烧钢渣有利于磁选而不利于电选。     

Separation of Toxic Organotin Compounds from Aqueous Solution by Adsorption

Abstract

The adsorption characteristics of organotin compound (tributyltin oxide) are established on activated carbons, polymeric adsorbent, and synthetic carbonaceous adsorbents. Maximum adsorptive capacity is obtained with activated carbon containing high percentage of macropores (100–500 Å). For this carbon the adsorptive capacity (g organotin adsorbed/g of adsorbent) at breakpoint is 0.30 and the capacity at exhaustion (with 30 mg/L organotin solution) is 0.50.     

一种快速酶解糖化白蛋白的方法

建立了一种快速酶解糖化白蛋白的方法,通过在含有低浓度蛋白酶和蛋白变性剂的酶解液中添加一定浓度的离子液体用于提高蛋白酶的活性和稳定性,使糖化白蛋白在180~600s内快速酶解。该方法特别适合FAOD法测定糖化白蛋白的方法学及测定试剂开发。