不同晶型甘氨酸在水中溶解度的测定与关联

不同晶型甘氨酸溶解度的测定对研究甘氨酸结晶及多晶型现象具有重要意义。采用激光动态法测定了15~80℃范围内α型和γ型甘氨酸在纯水中的溶解度数据,并且采用Apelb lat溶解度经验方程对实验数据进行了关联,回归了溶解度经验方程的参数,关联效果令人满意。实验结果表明,在水中α和γ甘氨酸溶解度均随温度升高而变大;在相同温度下,热力学亚稳的α型甘氨酸比稳态的γ型甘氨酸溶解度大。     

甘氨酸受体在肾细胞缺氧保护中的作用研究

目的明确甘氨酸受体(glycine receptor,GlyR)是否介导甘氨酸对ATP耗竭细胞的保护作用。方法构建甘氨酸受体α1亚单位(GlyRα1)的真核表达载体pcDNA3.1(b),转染入缺乏天然GlyR的人胚胎肾细胞HEK293。化学性缺氧使细胞处于ATP耗竭状态,光学显微镜及电镜观察细胞形态及超微结构改变,LDH释放率、细胞膜对荧光标记复合物通透性反映细胞膜完整性,台盼蓝染色观察细胞活性。结果细胞ATP耗竭3h后,细胞膜通透性明显增加,细胞器结构损伤,大量细胞死亡。甘氨酸明显降低表达GlyR的转染HEK293细胞膜通透性,阻止荧光标记复合物进入细胞内,细胞LDH释放率由59.18±8.10%下降为35.15±2.61%。从而维持细胞形态结构,降低细胞死亡率。对不表达GlyR细胞无保护作用。结论GlyR介导甘氨酸对ATP耗竭细胞的保护作用,增强细胞对ATP耗竭的耐受能力,增加细胞的存活几率。     

Mutational Analysis of the Absolutely Conserved B8Gly： Consequence on Foldability and Activity of Insulin

B8Gly is absolutely conserved in insulins during evolution. Moreover, its corresponding position is always occupied by a Gly residue in other members of insulin superfamily. Previous work showed that Ala replacement of B8Gly significantly decreased both the activity and the foldability of insulin. However, the effects of substitution are complicated, and different replacements sometimes cause significantly different results. To analyze the effects of B8 replacement by different amino acids, three new insulin/single-chain insulin mutants with B8Gly replaced by Ser, Thr or Leu were prepared by protein engineering, and both their foldability and activity were analyzed. In general, replacement of B8Gly by other amino acids causes significant detriment to the foldability of single-chain insulin： the conformations of the three B8 mutants are essentially different from that of wild-type molecules as revealed by circular dichroism; their disulfide stabilities in redox buffer are significantly decreased; their in vitro refolding efficiencies are decreased approximately two folds; the structural stabilities of the mutants with Set or Thr substitution are decreased significantly, while Leu substitution has little effect as measured by equilibrium guanidine denaturation. As far as biological activity is concerned, Ser replacement of B8Gly has only a moderate effect： its insulin receptor-binding activity is 23% of native insulin. But Ttir or Leu replacement produces significant detriment： the receptorbinding potencies of the two mutants are less than 0.2% of native insulin. The present results suggest that Gly is likely the only applicable natural amino acid for the B8 position of insulin where both foldability and activity are concerned.     

光敏核不育水稻幼穗的乙烯生成与育性转换

研究了在不同光温组合下光敏核不育水稻（ＰＧＭＲ）农垦５８５（ＮＫ５８Ｓ）及普通水稻品种农垦５８（ＮＫ５８Ｂ）的幼穗乙烯生物合成变化及其与育性表达的关系。结果表明ＮＫ５８Ｓ幼穗乙烯生成受光周期和温度的共同调节,而光周期对ＮＫ５８Ｂ幼穗乙烯生成无明显影响。ＮＫ５８Ｓ幼穗乙烯生成的变化与育性转换光温作用模式完全吻合。其幼穗乙烯释放速率（ＥＲＲ）与花粉可育度（ｌｎｙ）呈极显著负相关。用ＡＶＧ抑制乙烯生成可使ＮＫ５８Ｓ（ＬＤ）不育性明显逆转,而用ＡＣＣ促进乙烯生成又可急剧降低ＮＫ５８Ｓ（ＳＤ）的可育水平。表明幼穗乙烯生成与ＰＧＭＲ育性表达密切相关,乙烯参与育性转换的调控并可能起着重要作用。     

MPG静注减轻清醒狗缺血后心肌顿抑

为了解自由基清除剂２巯基丙酰基甘氨酸（ＭＰＧ）能否减轻缺血后心肌顿抑,本文报告了在清醒狗模型中氧自由基清除剂ＭＰＧ对缺血后心肌顿抑的疗效。３９只清醒狗模型阻闭前降支１５ｍｉｎ后再灌注４８ｈ。治疗组（ｎ＝１７）于阻闭前１５ｍｉｎ始静脉给予ＭＰＧ（１００ｍｇ／ｋｇ·ｈ）,共持续６０ｍｉｎ,对照组（ｎ＝２２）给予生理盐水。结果表明,二组缺血区侧支血流、缺血区大小及血液动力学指标无显著差异,而治疗组室壁收缩增厚指数（一种局部心肌功能指标）于再灌注后２、３、４、５、６ｈ明显大于对照组,当侧支血流低于１０％时,改善更明显。指数回归分析结果显示,治疗组侧支血流越低,收缩功能恢复程度越明显。结论,ＭＰＧ可以促进缺血后心肌顿抑的恢复,这种有益的疗效在低侧支血流时更明显。     

5-HT和NA增强大鼠骶髓后连合核神经元甘氨酸门控Cl~-通道电流由蛋白激酶介导

用制霉菌素穿孔膜片钳方法研究５－ＨＴ和ＮＡ对急性分离的大鼠骶髓后连合核神经元甘氨酸门控氯离子通道电流（ＩＧｌｙ）的调控作用及其胞内机制。发现：（１）５－ＨＴ激活与非胰岛激活蛋白（ＩＡＰ）敏感型Ｇ蛋白偶联的５－ＨＴ２受体亚型,激活磷脂酶Ｃ（ＰＬＣ）,增加甘油二酯（ＤＡＧ）的生成。ＤＡＧ增强不依赖Ｃａ２＋的新型ＰＫＣ（ｎＰＫＣ）的活性,从而增强ＩＧｌｙ;（２）ＮＡ激活与ＩＡＰ敏感型Ｇ蛋白偶联的α２受体,抑制腺苷酸环化酶（ＡＣ）,减少ｃＡＭＰ的生成,使ＰＫＡ活性降低,从而增强ＩＧｌｙ。     

N－（膦羧甲基）α－甘氨酸的合成与应用

叙述了Ｎ－（膦羧甲基）α－甘氨酸的化学合成及其在除草剂方面的应用。该化合物有五条合成路线：曼尼斯反应、加成反应、取代反应、氧化还原反应和其他反应。其中曼尼斯反应较简便,可由甘氨酸、甲醛和亚磷酸酯一步合成标题化合物。Ｎ－（膦羧甲基）α－甘氨酸是一种高效广谱内吸传导型叶片喷药除草剂,它能有效地控制世界上危害最大的７８种恶性杂草中的７６种,还能“斩草除根”。除草机理为竞争性抑制５－烯醇丙酮莽草酸－３－磷酸合成酶（ＥＰＳＰａｓｅ）。     

丙肝病毒融合抗原基因NS3-C定点整合入衣藻 叶绿体基因组的研究

用PCR方法从丙型肝炎病毒(HCV) cDNA文库中克隆了两段DNA片段,即HC基因组非结构NS3区抗原基因(约0.7 kb)和核心抗原C区抗原基因(约0.6 kb)的cDNA片段。在两段cDNA间加入连接肽Ser-Pro-Gly-Ser的密码子序列,构建成融合抗原基因NS3-C。将该融合基因与衣藻叶绿体基因atpA的启动子和rbcL基因的3'末端连接,得到丙肝病毒融合抗原基因NS3-C表达盒,再将该表达盒与选择标记基因aadA表达盒和衣藻叶绿体基因组同源片段连接,构建成衣藻叶绿体转化载体pSS6。基因枪法转化衣藻叶绿体,经壮观霉素筛选获得转化再生的单藻落,对转基因衣藻的PCR和Southern杂交分析表明,融合抗原基因NS3-C已整合到衣藻叶绿体基因组中。 Abstract:　Two DNA fragments encoding the nucleocapsid (C) region protein and the non-structural region 3 (NS3) protein of hepatitis C virus(HCV) were amplified from cDNA library by using PCR method. The 5' terminal of C cDNA fragment was linked up with the 3' terminal of NS3 cDNA fragment by a oligonucleotide linker Ser-Pro-Gly-Ser to form a chimeric gene NS3-C, which was placed under the control of the chloroplast atpA promoter and rbcL 3' region of Chlamydomonas reinhardtii to construct the chimeric gene NS3-C cassette. Then the NS3-C cassette was linked with selectable gene aadA cassette and the chloroplast homologous fragments of Chlamydomonas reinhardtii to generate transformation vector pSS6. Chloroplasts of Chlamydomonas reinhardtii were transformed by particle bombardment. Plastid transformants were selected by their resistance to 100 mg/L of spectinomycin. PCR and Southern hybridization analysis showed that the chimeric gene NS3-C had been integrated into chloroplast genome of Chlamydomonas reinhardtii.