工业合成甘氨酸其含量的测定——甲醛法

<正> 甘氨酸是医药、有机合成和生物化学研究中常用的氨基酸之一。工业上,甘氨酸可由一氯醋酸和氢氧化铵作用而成。而工业合成甘氨酸其含量的测定目前尚无国家标准。上海市卫生局药品检验标准中,甘氨酸的含量测定,采用高氯酸—冰乙酸非水滴定法。其它氨基酸的含量测定在工业上和医药上亦主要采用非水滴定和克氏定氮法,但是工业合成甘氨酸,由于其样品中有氯化铵的存在,用以上两法测定其准确性均受干扰。本文介绍用过量的氧化镁去除NH_3,在     

信息库

1.营养对热嗜酸梭菌生产醋酸的影 响 用热嗜酸梭菌（Clostridium thermoaceticum）生产醋酸比传统醋酸法有很多好处。首先,热嗜酸梭菌生产醋酸是一种厌氧过程,应该比传统的需氧酿醋法便宜。其次,它至少可以利用生物原料衍生的三种糖（木糖,果糖和葡萄糖）,并且醋酸的产量较高。理论上每克葡萄糖产醋酸一克,实际报道的产量是0.8—0.93克。热嗜酸梭菌是一种同型乙酸产生菌,可以醋酸为其唯一产物。它的主要限制是野生型菌株产酸浓度较低（～20g/l）,产率也较低（0.15—0.25g/l/h）。本实验室最近培育的菌株（ATCC 49707）产醋酸量比亲本（野生型）菌株高5倍;但是,这个菌株和其他高产菌株一样,培养和产醋要求的营养条件较高。用它来生产醋酸钠（一种酸化剂）,醋酸钾(一种热交换液）,和醋酸钙镁（CMA,一种道路化冰剂）等的成本价（例如每公斤葡萄糖＄0.16,每公斤酵母提取物的最低价＄8.5;     

醋酸氯己定与乙醇的协同杀菌效果

采用悬液定量杀菌试验,对醋酸氯己定与乙醇的协同杀菌效果进行了实验室研究。研究发现,0.1%醋酸氯己定与75%乙醇混合溶液对金黄色葡萄球菌、大肠埃希菌、白假丝酵母菌和黑曲霉均呈现出显著的协同杀菌作用。结果表明,醋酸氯己定与乙醇具有良好的协同杀菌效果。     

日本中野醋店和东京大学确立了醋化醋杆菌基因自体克隆技术

日本中野醋店已确立了食醋商业化生产所用的醋化醋杆菌(醋酸菌)(Acetobacter acefi)的有用基因自体克隆的基础技术。利用这项成果,就可使由限制性酶切断的DNA片断连接到载体上使其克隆化,使从得到的许多克隆通过散弹枪法(shot gun)克隆找出目标基因的技术能在醋酸菌中进行,从而可加快醋酸菌有用基因的克隆化。该公司正利用基因重组技术从事这种菌的育种工作:能降低醋酸发酵的冷却成本的高温发酵醋酸菌,有利于业务用食醋的高酸度发酵醋酸菌,提高醋酸发酵生产速度的醋酸菌等。     

醋酸氯己定的杀菌效果

采用悬液定量杀菌试验,对醋酸氯己定的杀菌效果进行实验室研究。研究发现,0.1%醋酸氯己定对金黄色葡萄球菌、大肠埃希菌、枯草芽胞杆菌、白假丝酵母菌和黑曲霉均具有明显的杀菌作用。通过模拟现场试验,醋酸氯己定起到了显著的杀菌效果。     

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。     

花背蟾蜍蝌蚪发生类坏死的皮肤在恢复过程中的超微结构

本实验以花背蟾蜍后肢芽期的蝌蚪为材料,用0.001 mol/L氨水(氨水组)和0.01mol/L醋酸(醋酸组)处理皮肤使之发生类坏死。以细胞核、细胞表面、细胞质及细胞间隙等的超微结构变化为指标,研究了各组皮肤发生类坏死后恢复过程中的可逆变化。结果观察到:两组均能引起核染色质浓缩,粘液分泌,液泡增多,线粒体及内质网膨大变形,细胞间隙变窄;醋酸还引起张力原纤维的凝集及紊乱等。恢复过程中,细胞核内染色质的分布趋于均匀,粘液的分泌渐正常,液泡减少,线粒体及内质网的形态逐步恢复,但细胞间隙一直很??窄;醋酸组中张力原纤维恢复成束且排列较整齐。作者认为氨水及醋酸引起蝌蚪皮肤发生类坏死后,在一定时间内是可以恢复的,而且此可逆变化也反映在超微结构的变化上。     

发生类坏死蝌蚪皮肤在诱导并分化为角膜过程中的超微结构

本研究以花背蟾蜍后肢芽期的蝌蚪为材料,以0.001 mol/L氨水(氨水组)和0.01mol/L醋酸(醋酸组)处理皮肤使之发生类坏死,研究发生类坏死的皮肤移植片,在被诱导并分化为角膜过程中的超微结构变化。结果发现:各组细胞表面粘液经历了由少到多,再到少的过程;在皮肤片细胞去分化中,黑色素颗粒逐步消失,其中以氨水组最快,醋酸组次之;细胞间隙在氨水组及醋酸组中均较对照组为窄;实验组胶原纤维趋于均匀的速度较对照组为快。作者认为:类坏死处理导致去分化的加速,粘液的增多,细胞间隙的变窄,以及促进胶原纤维趋于均匀等,与皮肤片透明的加速之间有一定的关系。本文对类坏死与加速皮肤片被诱导和分化为角膜进程间的可能关系进行了讨论。     

高效氯氟氰菊酯微囊悬浮剂与二阶段法对红火蚁的田间防治效果评价

研究了高效氯氟氰菊酯微囊悬浮剂与二阶段法对红火蚁的田间防治效果。结果表明,0.25 g/L高效氯氟氰菊酯微囊悬浮剂施药后击倒红火蚁迅速,14 d后活动蚁巢减退率、工蚁减退率、蚁巢级别降低率、综合防治效果均达到100%。使用0.045%茚虫威饵剂搭配0.25 g/L高效氯氟氰菊酯微囊悬浮剂的二阶段法,5 d后红火蚁的活动蚁巢和工蚁数量均显著下降,14 d后活动蚁巢减退率、工蚁减退率、蚁巢级别降低率、综合防治效果均达到100%。结果表明,0.25 g/L高效氯氟氰菊酯微囊悬浮剂对红火蚁具有高效的控制作用,在实际使用时可根据防治面积的大小选择单独灌巢还是配合饵剂的二阶段法。     

脑啡肽基因的合成——Ⅰ.d-GATCCTAGA的合成

本文报道了脑啡肽基因下链二十六核苷酸中九核苷酸d-GATCCTAGA的合成。合成系采用改良的三酯法,即先合成和三个片段,然后由脱去5'-Dmt基后依次同和向5'端延伸缩合得到产物和是通过和分别同过量的d-T缩合,然后再用对氯苯磷酰双三唑对产物的3'-OH进行磷酰化得到。则是由同反应得到。在所有的缩合反应中,都采用2,4,6-三甲基苯磺酰硝基咪唑为缩合剂,缩合产物都以硅胶短柱层析分离纯化。除保护的九核苷酸未进行硅胶柱层析纯化之外,各中间片段经硅胶柱层析纯化后的收率都在75%以上。合成的全保护九核苷酸用浓氨水和80%醋酸相继脱去全部保护基后,以DEAE-葡聚糖凝胶A-25柱层析(含7M尿素)分离纯化,经去盐后得到d-GATCCTAGA,收率31.7%。产物的5'-OH用~(32)P标记后,同系层析均一,蛇毒磷酸二酯酶部分酶解后,作电泳-同系层析双向图谱,证明核苷酸排列顺序正确。     

Investigation of the mechanism of temperature sensitivity of the electroreceptors of ampullae of lorenzini

In experiments on Black Sea skates (Raja clavata), the potential of the receptor epithelium of the ampullae of Lorenzini and spike activity of single nerve fibers connected to them were investigated during electrical and temperature stimulation. Usually the potential within the canal was between 0 and –2 mV, and the input resistance of the ampulla 250–400 k. Heating of the region of the receptor epithelium was accompanied by a negative wave of potential, an increase in input resistance, and inhibition of spike activity. With worsening of the animal's condition the transepithelial potential became positive (up to +10 mV) but the input resistance of the ampulla during stimulation with a positive current was nonlinear in some cases: a regenerative spike of positive polarity appeared in the channel. During heating, the spike response was sometimes reversed in sign. It is suggested that fluctuations of the transepithelial potential and spike responses to temperature stimulation reflect changes in the potential difference on the basal membrane of the receptor cells, which is described by a relationship of the Nernst's or Goldman's equation type.I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. I. M. Sechenov, Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Pacific Institute of Oceanology, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Neirofiziologiya, Vol. 12, No. 1, pp. 67–74, January–February, 1980.     

Principles of organization and evolution of systems of regulation of functions

Evolution of living organisms is closely connected with evolution of structure of the system of regulations and its mechanisms. The functional ground of regulations is chemical signalization. As early as in unicellular organisms there is a set of signal mechanisms providing their life activity and orientation in space and time. Subsequent evolution of ways of chemical signalization followed the way of development of delivery pathways of chemical signal and development of mechanisms of its regulation. The mechanism of chemical regulation of the signal interaction is discussed by the example of the specialized system of transduction of signal from neuron to neuron, of effect of hormone on the epithelial cell and modulation of this effect. These mechanisms are considered as the most important ways of the fine and precise adaptation of chemical signalization underlying functioning of physiological systems and organs of the living organism