蛋氨酸脑啡肽质量标准研究

建立了蛋氨酸脑啡肽的质量标准。采用液相色谱-质谱联用仪检测蛋氨酸脑啡肽分子量和鉴别蛋氨酸脑啡肽的各氨基酸组成,反相高效液相色谱测定蛋氨酸脑啡肽含量。蛋氨酸脑啡肽分子量为573.7,氨基酸组成为Tyr-Gly-Gly-Phe-Met。蛋氨酸脑啡肽质量浓度在7~280 mg/L(r=0.999 8)内线性关系良好,平均回收率为98.54%,RSD为0.89%。所建立的方法科学,可靠,重复性好。可准确地对蛋氨酸脑啡肽进行定性定量检测。     

黑加仑果酒花青素测定方法的确定及营养成分分析

利用p H示差法对黑加仑浆果及其果酒花青素的含量进行测定,结果表明花青素的最佳检测条件为:检测波长541 nm,p H 1.0和p H 4.5,平衡时间50 min,样品p H 3.0,此方法精密度和回收率的RSD值分别为1.34%和3.01%,测得果实和果酒中花青素含量分别为2.01 g/L和0.64g/L。通过高效液相色谱和原子吸光光度法对黑加仑果酒的营养成分进行分析,结果表明酒体中共含有17种氨基酸,总量达1 173.45 mg/L,其中7种必需氨基酸,含量占29.2%;并含有人体所必需的矿质元素,其中K、Ca的含量较高,分别为1 865 mg/L和510.5 mg/L,此外,黑加仑果酒的总酚含量为3.87 g/L。     

不同浓度蛋氨酸硒对南瓜种子的萌发和幼苗生长的影响

本研究采用蛋氨酸硒溶液对"金香栗"南瓜种子进行浸种处理,通过测定南瓜种子的发芽率、发芽指数、POD活性、脯氨酸和丙二醛含量5个指标,研究不同浓度的蛋氨酸硒对南瓜的种子的萌发和幼苗的生长的影响。从而筛选出合适的蛋氨酸硒溶液浓度,实现富硒南瓜安全有效生产与推广。结果表明:0~20 mg/L的蛋氨酸硒溶液处理南瓜种子可明显提高南瓜种子的发芽指数、发芽率和POD活性,降低了丙二醛和脯氨酸含量。因此,0~20 mg/L蛋氨酸硒溶液可促进南瓜种子的萌发和幼苗的生长,且最适宜的蛋氨酸硒浓度为8 mg/L。     

高效液相色谱法测定17AA氨基酸注射液中N-乙酰-L-半胱氨酸和N-乙酰-L-酪氨酸

建立了一种用高效液相色谱测定 17AA氨基酸注射液中N 乙酰 L 半胱氨酸和N 乙酰 L 酪氨酸含量的方法。样品经稀释后 ,直接上机测定 ,其色谱条件为 :WatersSymmetryC18色谱柱 ,流动相为 8.5mmol/LNaAc - 5 %CH3 OH (pH =4.0 ) ,柱温36℃ ,流速 1.0ml/min ,检测波长 195nm ,N 乙酰 L 半胱氨酸在 5 .4mg/L到 5 40mg/L、N 乙酰 L 酪氨酸在 4.9mg/L到 490mg/L之间 ,标准曲线呈良好的线性关系 (r2 >0 .9999)。该方法具有良好的重现性 ,日内相对标准偏差小于 3% ,日间相对平均误差小于 7% ,样品回收率在 90 %～ 110 %之间。该方法与测定氨基酸注射液的其它高效液相色谱法相结合 ,能够对 17AA氨基酸注射液中所有氨基酸成分进行全面检测。     

119种植物种子蛋氨酸含量分析

豆科植物蛋白中含硫氨基酸尤其是蛋氨酸含量低,影响其蛋白质的营养价值。为开发出更高甲硫氨酸含量蛋白质基因资源,采用酸水解法,对我国亚热带常见的119种森林植物种子的蛋氨酸含量进行了测定。结果表明:93%以上植物种子的蛋氨酸含量较低,只有八仙花、榕叶冬青、山苍子、锌树、龙葵、栾树、商陆和盐肤木的蛋氨酸含量在10.00mg/g以上,其中盐肤木的蛋氨酸含量为119种植物中最高,达36.89mg/g,可以作为进一步开发的新型高蛋氨酸蛋白基因资源。     

食品中农药残留的高通量微生物检测方法研究

目的甲胺磷的微生物高通量定量分析法,并在待检蔬菜样品进行初步的探索。方法以短双歧杆菌LJM-006作为测试菌,选择浓度为0、0.25、0.5、1.0、2.0和4.0 mg/L的甲胺磷标准品溶液20μL加入所述检测管内,37℃厌氧培养8～10 h,分别测定反应管和阴性对照反应管的A500值,B值为样品反应管的A500值,B0值为阴性对照反应管的A500值;以B/B0为纵坐标Y,甲胺磷浓度的对数值为横坐标X,绘制标准曲线,建立甲胺磷含量与B/B0的线性回归方程;以此方法进行模拟食品样品中所含甲胺磷检测,进行准确度、精密度分析。结果双歧杆菌菌株LJM-006对甲胺磷敏感性高,与其他有机磷农药的交叉反应率均小于2%;在0.01～100 mg/L浓度范围内B/B0与甲胺磷浓度对数值的线性关系良好,甲胺磷检测的标准曲线为Y=-24.68X＋66.72,R2为0.9902,IC50=0.25 mg/L,检测下限达到0.1 mg/L,回收率为78.5%～105.7%,批内变异系数≤12%,批间变异系数≤8.2%。结论该方法具有操作简便,具备一定灵敏度和特异性等优点,可作为一种食品中甲胺磷残留筛检方法。     

反相高效液相色谱法测定双唑泰软膏中三组分的含量

以C_(18) ODS色谱柱为分析柱,甲醇-水-三乙胺(体积比70:30:0.3,含庚烷磺酸钠10mmol/L,用磷酸调pH 4.0)为流动相,260 nm为检测波长,用反相高效液相色谱法测定了双唑泰软膏中甲硝唑、克霉唑和醋酸氯己定3个组分的含量。测定结果表明:甲硝唑、醋酸氯己定和克霉唑分别在3.92～39.2μg/mL,3.32～33.2μg/mL和1.64～16.4μg/mL质量浓度范围内,与峰面积呈良好的相关性(r=0.999 9、r=0.999 4和r=0.999 1),平均回收率分别为99.95%、101.14%和99.47%(n=9)。该法快速、方便,分离度好,辅料无干扰,适用于该复方制剂中3种成分的同时测定。     

生物活性肽——蛋氨酸脑啡肽治疗白血病一例报告

蛋氨酸脑啡肽是内源性阿片样物质。它是由5个氨基酸残基组成的多肽,其第5位氨基酸残基为蛋氨酸。通过抽取病人静脉血,分离淋巴细胞,进行体外扩增激活,然后回输患者体内,患者外周血白细胞计数为3．6×10^9／L,血红蛋白122g/L,血小板116×10^9／L,异常淋巴细胞消失,幼粒细胞消失。骨髓象示粒细胞系统、红细胞系统增生活跃,各阶段细胞比值及形态大致正常;淋巴细胞比值减低,形态正常;造血功能恢复。由此可见,蛋氨酸脑啡肽体外激活免疫系统并回输体内作为一种新的治疗白血病的方法,具有广泛的应用前景。     

RP-HPLC测定红丝线提取物中紫蓝素的含量

建立了红丝线提取物中紫蓝素的测定方法。采用反相高效液相色谱法,色谱柱为ZORBAXXDB-C18(4.6mm×150mm,5μm);流动相:V(乙腈):V[75mmol/L乙酸铵+0.5mmol/LEGTA(pH7.0)]=8∶92;流速:1mL/min;检测波长590nm。紫蓝素的线性范围为2.5～50mg/L(r=0.9999),回收率97.9%～101.5%。该法简便、准确,重复性好,适用于测定红丝线提取物中紫蓝素的含量。     

苯酚消毒剂中邻苯基苯酚和对叔戊基苯酚的高效液相色谱测定法

目的建立同时测定苯酚消毒剂中的邻苯基苯酚和对叔戊基苯酚2种杀菌有效成分的高效液相色谱法。方法采用安捷伦ZorbaxODS,25cmx4.6mm,粒径5μm的反相色谱柱,流动相为乙腈-1%醋酸溶液(60:40),流速1.5mL/min,检测波长278nm,柱温为25℃下进行检测。结果邻苯基苯酚和对叔戊基苯酚的线性范围为5~150mg/L,相关系数为0.9999,检出限为5mg/L,相对标准偏差小于1.02%,加标回收率为93.6%~98.5%。结论该方法操作简便、快速、灵敏度高,适合消毒剂中的邻苯基苯酚和对叔戊基苯酚的同时测定。     

壳聚糖酶的克隆表达与壳寡糖的制备分析

目的:克隆壳聚糖酶基因于大肠杆菌中实现高表达,制备壳寡糖。方法:以枯草芽孢杆菌总DNA为模板扩增壳聚糖酶基因(CSN),克隆至载体pET23a(+)上,转化菌株BL21(DE3)。重组子经0.5 mmol/L IPTG诱导后,SDS-PAGE和质谱检测与鉴定重组酶。酶纯化后水解壳聚糖,薄层色谱分析其水解产物。结果:质谱证明壳聚糖酶(31.5kDa)成功表达,表达量占菌体总蛋白的45%左右。纯化后重组酶浓度为900 mg/L,纯度95%、回收率85%,酶活力为10 000 U/mg。壳聚糖降解产物为壳二糖至壳四糖。结论:原核表达载体pET23a(+)-CSN构建正确,壳聚糖酶表达量与活性高,适用于水解壳聚糖制备壳寡糖。     

国内外蝗害治理技术现状与展望

本文首先概述了国内外蝗虫发生与为害的态势,总结了现阶段我国蝗虫发生与为害的主要特点:即农田飞蝗暴发频繁而且严重,草原土蝗的发生时常造成严重的经济损失,而且侵入城市干扰市民生活,我国与周边国家之间蝗虫过境迁移频繁,使用化学农药污染环境和农产品;分析了国内外蝗虫防治对策与技术的发展现状,重点介绍了应急防治和可持续治理对策、...     

Coiled-coil nanomechanics and uncoiling and unfolding of the superhelix and alpha-helices of myosin

The nanomechanical properties of the coiled-coils of myosin are fundamentally important in understanding muscle assembly and contraction. Force spectra of single molecules of double-headed myosin, single-headed myosin, and coiled-coil tail fragments were acquired with an atomic force microscope and displayed characteristic triphasic force-distance responses to stretch: a rise phase (R) and a plateau phase (P) and an exponential phase (E). The R and P phases arise mainly from the stretching of the coiled-coils, with the hinge region being the main contributor to the rise phase at low force. Only the E phase was analyzable by the worm-like chain model of polymer elasticity. Restrained molecular mechanics simulations on an existing x-ray structure of scallop S2 yielded force spectra with either two or three phases, depending on the mode of stretch. It revealed that coiled-coil chains separate completely near the end of the P phase and the stretching of the unfolded chains gives rise to the E phase. Extensive conformational searching yielded a P phase force near 40 pN that agreed well with the experimental value. We suggest that the flexible and elastic S2 region, particularly the hinge region, may undergo force-induced unfolding and extend reversibly during actomyosin powerstroke.     

Synthesis of hapten and conjugates of coumestrol and development of immunoassay

3-O-Carboxymethylcoumestrol was prepared as the hapten for immunoassay by a partial alkylation of coumestrol with ethyl chloroacetate in acetone alkalized with potassium carbonate. 3-O-Ethoxycarbonylmethylcoumestrol was separated by column chromatography and finally was hydrolyzed with formic acid. 1H and 13C NMR data (APT, COSY, HMQC, and HMBC) revealed that the reaction was regioselective, as 3-O-ethoxycarboxymethylcoumestrol was the only monosubstituted derivative. The hapten was then conjugated to bovine serum albumin and used for immunization of rabbits. A radioimmunoassay (RIA) system was established based on the polyclonal antiserum and a 125I-labeled hapten-tyrosine methyl ester conjugate as the radioligand. Parameters of the RIA: sensitivity: 12 pg per tube, 50% intercept: 140 pg per tube, working range: 20-4000 pg per tube. The cross-reactivity of a panel isoflavonoid and lignan phytoestrogens was either negligible (e.g. formononetin 0.07%; biochanin A 0.06%) or not detectable at all. The major immunoreactive peak in HPLC fractions from an alfalfa extract had the same retention time as coumestrol standard and represented 94.8% of the signal. The remaining 5.2% of immunoreactivity was distributed between five minor peaks. We conclude that after the validation for particular matrices, the method will be a useful tool for analysis of coumestrol, especially in low volume and low concentration samples.     

Kinetics and thermodynamics of peroxidase- and laccase-catalyzed oxidation of N-substituted phenothiazines and phenoxazines

N -substituted phenothiazines (PTs) and phenoxazines (POs) catalyzed by fungal Coprinus cinereus peroxidase and Polyporus pinsitus laccase were investigated at pH 4–10. In the case of peroxidase, an apparent bimolecular rate constant (expressed as k _cat/K _m) varied from 1 ×10⁷M⁻¹s⁻¹to 2.6×10⁸M⁻¹s⁻¹ at pH 7.0. The constants for PO oxidation were higher in comparison to PT. pH dependence revealed two or three ionizable groups with pK _a values of 4.9–5.7 and 7.7–9.7 that significantly affected the activity of peroxidase. Single-turnover experiments showed that the limiting step of PT oxidation was reduction of compound II and second-order rate constants were obtained which were consistent with the constants at steady-state conditions. Laccase-catalyzed PT and PO oxidation rates were lower; apparent bimolecular rate constants varied from 1.8×10⁵M⁻¹s⁻¹ to 2.0×10⁷M⁻¹s⁻¹ at pH 5.3. PO constants were higher in comparison to PT, as was the case with peroxidase. The dependence of the apparent bimolecular constants of compound II or copper type 1 reduction, in the case of peroxidase or laccase, respectively, was analyzed in the framework of the Marcus outer-sphere electron-transfer theory. Peroxidase-catalyzed reactions with PT, as well as PO, fitted the same hyperbolic dependence with a maximal oxidation rate of 1.6×10⁸M⁻¹s⁻¹ and a reorganization energy of 0.30 eV. The respective parameters for laccase were 5.0×10⁷M⁻¹s⁻¹ and 0.29 eV. Received: 20 September 1999 / Accepted: 24 February 2000     

白术同源四倍体的诱导和鉴定及其与二倍体过氧化物酶的比较

以白术（Atractylodes macrooephala Koidz.）二倍体组培苗为材料,对其四倍体诱导方法进行研究,共获得45个白术同源四倍体株系,为优良株系的选育提供了材料。此外,还分析比较了其中8个白术四倍体株系与二倍体的过氧化物酶同工酶（POD）的酶谱差异,发现四倍体各株系过氧化物酶同工酶谱比二倍体的均多了Rf0.310的谱带,且总过氧化物酶比活力也发生了很大改变,对探讨白术四倍体优良株系的生理生化机理具有一定的参考价值。     

放牧对牧草光合作用、呼吸作用和氮、碳吸收与转运的影响

研究放牧对草地植物生理活动的影响,对于揭示草地放牧演替的生理机制有重要意义.大量研究表明,家畜放牧对牧草光合作用、呼吸作用以及C和N吸收与转运的影响,可以分为生理伤害和生理恢复2个阶段.放牧通过改变草地冠层结构影响牧草光合作用,净光合作用速率短期内迅速下降,随着叶面积指数增加又逐渐上升,呼吸作用有相似的变化趋势.牧草放牧后再生长所需的C和N最初主要来自根系和留茬中的贮藏物质,此后随着牧草生长恢复逐渐由同化作用供给,C代谢与土壤N水平负相关.放牧后牧草生理活动变化与牧草遗传特性、种间竞争、家畜放牧特征、非生物环境等因素密切相关.