Involvement of the MetO/Msr System in Two Acer Species That Display Contrasting Characteristics during Germination

The levels of methionine sulfoxide (MetO) and the abundances of methionine sulfoxide reductases (Msrs) were reported as important for the desiccation tolerance of Acer seeds. To determine whether the MetO/Msrs system is related to reactive oxygen species (ROS) and involved in the regulation of germination in orthodox and recalcitrant seeds, Norway maple and sycamore were investigated. Changes in water content, MetO content, the abundance of MsrB1 and MsrB2 in relation to ROS content and the activity of reductases depending on nicotinamide adenine dinucleotides were monitored. Acer seeds differed in germination speed—substantially higher in sycamore—hydration dynamics, levels of hydrogen peroxide, superoxide anion radicals (O₂^•−) and hydroxyl radicals (•OH), which exhibited peaks at different stages of germination. The MetO level dynamically changed, particularly in sycamore embryonic axes, where it was positively correlated with the levels of O₂^•− and the abundance of MsrB1 and negatively with the levels of •OH and the abundance of MsrB2. The MsrB2 abundance increased upon sycamore germination; in contrast, it markedly decreased in Norway maple. We propose that the ROS–MetO–Msr redox system, allowing balanced Met redox homeostasis, participates in the germination process in sycamore, which is characterized by a much higher speed compared to Norway maple.     

胶束电动毛细管色谱法测定冬虫夏草中核苷及核苷碱基的含量

目的:测定冬虫夏草、虫体和子座部分核苷及核苷碱基的含量,为质量评定提供检测方法。方法:用胶束电动毛细管色谱法(MECC)测定,以黄嘌呤核苷为内标,电泳缓冲液为V(20mmol·L~(-1)硼砂,25mmol·L~(-1)十二烷基硫酸钠即SDS):V(乙腈)=95:5,电压25KV,柱温30℃,检测波长260nm,进样量5mmHg·S。结果:可同时测定出腺嘌呤(Ⅰ)、腺苷(Ⅱ)、次黄嘌呤(Ⅲ)、鸟苷(Ⅳ)、尿苷(Ⅴ)和次黄嘌呤核苷(Ⅵ)的含量,回收率分别为102.5％,102.7％,98.83％,101.1％,100.8％和101.4％,RSD小于2％。结论:正品虫草中都含有1～Ⅵ6个化合物,子座中Ⅰ～Ⅴ5个化合物的含量均明显高于虫体,虫草中Ⅱ、Ⅳ、Ⅴ、Ⅵ4种核苷的含量较高且相对稳定。     

生产烟酰胺新工艺技术

概述烟酰胺的国内外生产技术现状及市场需求情况 ;简要介绍以 2 甲基 1 ,5戊二胺为原料生产烟酰胺的新工艺流程及技术特点。     

天然烟酰胺辅因子再生体系及其人工类似物研究进展

氧化还原酶可以催化具有特定区域选择性、化学选择性、立体选择性的反应,反应条件温和且催化效率高,因此在有机化学和制药领域发挥着日益重要的作用。绝大多数氧化还原酶依赖烟酰胺腺嘌呤二核苷酸NAD（H）和烟酰胺腺嘌呤二核苷酸磷酸NADP（H）为酶促反应提供氧化还原当量。NAD（H）/NADP（H）由于价格昂贵、稳定性差导致无法化学计量投入。经过几十年研究,形成了4种经典的NAD（H）/NADP（H）再生方法：酶法、化学法、电化学法和光化学法,与此同时,一系列稳定性好、活性高且廉价的人工烟酰胺辅因子mNAD（H） s尤其是1,4-二氢吡啶类烟酰胺辅因子的开发和利用为NAD（H）/NADP（H）工业化运用提供了新的思路。     

Effect of NdCl_3 on the Growth and i_PA Level of Detached Etiolated Cotyledons of Brasica Chinensis

ＥｆｅｃｔｏｆＮｄＣｌ３ｏｎｔｈｅＧｒｏｗｔｈａｎｄｉＰＡＬｅｖｅｌｏｆＤｅｔａｃｈｅｄＥｔｉｏｌａｔｅｄＣｏｔｙｌｅｄｏｎｓｏｆＢｒａｓｉｃａＣｈｉｎｅｎｓｉｓＣｈｅｎＫａｏｓｈａｎ（陈靠山），ＺｈａｎｇＪｕｒｅｎ（张举仁）（ＢｉｏｌｏｇｙＤｅｐ...     

烟酰胺抑制人皮黑素细胞的适宜浓度研究

研究了烟酰胺对酪氨酸酶活性、人皮黑素细胞的增殖率、细胞周期动力学和黑素合成的影响。结果显示：烟酰胺体外抑制酪氨酸酶活性不明显；随浓度增加、作用时间的延长，烟酰胺抑制黑素细胞的增殖作用明显；0．25g／L烟酰胺加入24h后，细胞增殖指数明显下降，细胞多处于G0-G1期，S期细胞数量也显减少。实验发现：0．25g／L以上的烟酰胺均可以抑制黑素细胞中黑素合成，其中0．25g／L的烟酰胺可抑制黑素合成且对细胞损伤作用最小。故推荐0．25g／L的烟酰胺为安全、有效作用浓度。     

2’-脱氧腺苷的合成

以腺嘌呤(Ⅰ)和1-乙酰氧基-3,5-二(对甲基苯甲酰基)-2-脱氧核糖(Ⅱ)为原料,先将腺嘌呤进行硅醚保护,然后与Ⅱ催化缩合生成带保护基的2’-脱氧腺苷,脱保护基,得到-βD-2’-脱氧腺苷。考察了反应物(Ⅰ)和(Ⅱ)的摩尔比、催化剂的用量及反应温度对2’-脱氧腺苷收率的影响。结果表明,最佳反应条件为:(Ⅰ)∶(Ⅱ)(摩尔比)=1∶1,催化剂用量为0.54%,反应温度为20℃时,2’-脱氧腺苷的总收率可达65%。     

Monitoring of bioventing process for diesel-contaminated soil by dehydrogenase activity, microbial counts and the ratio ofn-alkane/isoprenoid

Monitoring parameters were evaluated for a bioventing process that was designed to treat soils contaminated with diesel fuel. Statistical analyses were conducted to evaluate correlations between total petroleum hydrocarbon concentrations in the contaminated soil and physico-chemical parameters of soil such as microbial counts, dehydrogenase activity, andn-alkane/isoprenoid ratio. The correlation coefficients (r²) obtained showed that TPH concentrations in the bioventing system were strongly correlated with dehydrogenase activity (DHA), total heterotrophic bacterial count, and hydrocarbon utilizing bacterial count. Thus, it was concluded that these parameters could useful monitoring parameters for soils contaminated with diesel fuel     

Relative binding free energy calculations of inhibitors to two mutants (Glu46-- Ala/Gln) of ribonuclease T1 using molecular dynamics/free energy perturbation approaches

We present free energy perturbation calculations on the complexesof Glu46— Ala46 (E46A) and Glu46— Gln46 (E46Q) mutantsof ribonuclease T1 (RNaseT1) with inhibitors 2‘-guanosinemonophosphate (GMP) and 2’adenosine monophosphate (AMP)by a thermodynamic perturbation method implemented with moleculardynamics (MD). Using the available crystal structure of theRNaseT1–GMP complex, the structures of E46A-GMP and E46Q-GMPwere model built and equilibrated with MD simulations. The structuresof E46A-AMP and E46Q-AMP were obtained as a final structureof the GMP—AMP perturbation calculation respectively.The calculated difference in the free energy of binding (Gbind)was 0.31 kcal/mol for the E46A system and —1.04 kcal/molfor the E46Q system. The resultant free energies are much smallerthan the experimental and calculated value of 3 kcal/mol forthe native RNase T1, which suggests that both mutants have greaterrelative adenine affinities than native RNaseT1. EspeciallyE46Q is calculated to have a larger affinity for adenine thanguanine, as we suggested previously from the calculation onthe native RNaseT1. Thus, the molecular dynamics/free energyperturbation method may be helpful in protein engineering, directedtoward increasing or changing the substrate specificity of enzymes.