蛋白质酶促水解反应机理与动力学模型

研究蛋白质酶促水解制备生物活性多肽的反应机理与动力学行为，并建模表征不同反应机制的酶解曲线。基于对不同实验条件下反应时程特性的分析，以经典的米氏方程为理论基础，提出了同时考虑蛋白质单底物水解、蛋白酶失活以及底物或产物抑制因素的机理模型，并构建了指数形式动力学方程dh／dt=aexp（-bh），其中参数（a和b对于不同反应机理具有不同的表达形式和确定的数值结果，对于牛血清白蛋白（BSA）-胰蛋白酶（trypsin）模型体系，经实验拟合平均相对误差为4．73％，并求得该体系相应热力学和动力学常数：Km=0．0748g/L，Ks=7．961g/L，Kd=9．358min^-1，K2=38．439min^-1，Ea=64．826kJ／mol，Ed=80．031kJ／mol。所建整套模型可用于蛋白质酶解反应过程的模拟、热动力学常数的计算和生物反应器的优化设计。     

一株海洋真菌Trichoderma sp.Q98合成产物分析

海洋真菌Trichoderma sp.Q98菌株有4个新颖特征:菌丝产生天然红色素;菌丝产生饱和脂肪酸(1.44% 14:0;17.52% 16:0)及不饱和脂肪酸(2.9% 16:1 (△9),39.16% 18:2 (△8,11),37.12% 18:3 (△9,12,15));培养液含有2组多肽类物质(毛细管电泳迁移时间分别为5.2 min和10.6 min);培养液原液对多重耐药性菌株EN(3)23(Ap r, Cm r, Sm r, Tet r, Ery r)具有强烈抑制作用.     

Genetic control of hippocampal cholinergic and dynorphinergic mechanisms regulating novelty-induced exploratory behavior in house mice

Summary Neurobehavioral genetics endeavors to trace the pathways from genetic and eenvironmental determinants to neuroanatomical and neurophysiological systems and, thence, to behavior. Exploiting genetic variation as a tool, the behavioral sequelae of manipulating these neuronal systems by drugs and antisera are analyzed. Apart from research in rats, this paper deals mainly with the genetically-influenced regulation in mice of exploratory behaviors that are adaptive in novel surroundings and are hippocampally-mediated. Special attention is paid to neuropeptidergic, GABAergic, and cholinergic synaptic functions in the mouse hippocampus.The behaviorally different inbred mouse strains C57BL/6 and DBA/2 show opposite reactions (reductions and increases, respectively, in exploration rates) to peripheral and intrahippocampal injections with agents that interfere with peptidergic, cholinergic, and GABAergic neurotransmission. These findings can be explained by an interdependent over-release of opioids, arrested GABA release, and excess acetylcholine in the hippocampal neuronal network of DBA/2 mice, as compared to C57BL/6 mice where these systems are functionally well balanced. Very similar results have been obtained with the lines SRH and SRL, derived from C57BL/6 and DBA/2, and genetically selected for rearing behavior. Most probably, the opioids act to disinhibit exploratory responses. An additional genetic approach is mentioned, in which four inbred mouse strains and one derived heterogeneous stock are used for estimating genetic correlations between structural properties of the hippocampal mossy fibers and levels of hippocampal dynorphin B, on the one hand, and frequencies of exploratory responses to environmental novelty, on the other.     

家蝇蛹血淋巴抗菌活性的诱导及相关蛋白/多肽的表达规律

对家蝇蛹血淋巴的抗菌活性进行了诱导，并用统计学逐步回归的方法和多项式回归的方法确定了抗菌相关蛋白／多肽，研究了其表达规律。结果表明，针刺、带菌针刺和超声波均能诱导家蝇蛹产生抗G^ 球菌的物质，而对G^-杆菌无效。在分子量低于18000的蛋白／多肽中，有两种物质（R5、R6）对抑菌活性有显著影响，它们的表观分子量分别在12000和7650左右，这两种蛋白／多肽均在诱导下表达。其中，R6对抑菌活性有极显著正贡献，而R5对抑菌活性有显著负贡献，推测R5为细胞生长促进因子。     

酶解制备贻贝抗氧化肽与功能性鱼糕的研制

开发具有抗氧化活性的功能性鱼糜制品。采用酶解法并筛选中性蛋白酶为最适蛋白酶制备贻贝抗氧化肽。利用正交设计优化酶解工艺条件,确定酶解温度45℃、酶解时间1h、酶添加量1500U/g、料液比(g/mL)1∶5为较优酶解工艺条件,在此条件下酶解产物多肽得率达到(73.62±0.86)mg/g。添加质量分数大于2%的经冷冻干燥的贻贝酶解产物到鱼糕中,检测其在鱼糕中对猪油的抗氧化作用,经方差分析得知其有显著的抗氧化作用。以此说明鱼糕是具有抗氧化性的功能性食品。     

Ethanol ingestive behavior as a function of central neurotransmission

Summary Uncontrollable alcohol ingestive behavior has been linked to deficits of central neurotransmission. The pineal gland plays an important role in modulating ethanol intake in numerous animal species. The opioidergic (i.e. -endorphin, enkephalin, and dynorphin) system is involved in both the actions of alcohol and opiates, as well as craving and/or genetic predisposition towards abuse of these two agents. Furthermore, there is significant evidence to link ingestive behaviors with the ventral tegmental accumbens-hypothalamic axis, whereby the biogenic amines dopamine and serotonin are reciprocally involved. Evidence is presented which implicates the striatum and the hypothalamus as possible specific loci for regional differences between alcohol-preferring and alcohol-nonpreferring mice. We believe that photoperiod-induced alcohol ingestive behavior may involve alterations in both pineal and hypothalamic opioid peptides.     

Natriuretic peptide hormones promote radial water movements from the xylem of Tradescantia shoots

Immunological evidence suggests that plants, like vertebrates, contain natriuretic peptides (NPs) and that rat atrial NP (rANP) binds specifically to plant membranes and promotes concentration and conformation-dependent stomatal opening. Stomatal opening and specific increases in cGMP levels were also observed in response to immunoreactive plant NP (irPNP). Here we report that both 1 μM rANP and irPNP (100 ng total protein/100 μL) significantly increase radial water movements out of the xylem of shoots of Tradescantia multiflora. Enhanced radial water movements are also observed in response to the cell permeant cGMP analogue 8-Br-cGMP (100 nM). The water channel inhibitor mercuric chloride (HgCl₂) significantly inhibits radial water movements at concentrations of 50 μM, while the presence of 10 μM 2-hydroxyethylmercaptoethanol (ME) prevents the inhibitory effect of the mercurial. The guanylate cyclase inhibitor LY 83583 at a concentration of 20 μM and sodium azide (NaN₃) at concentrations of ≥ 1 μM both also reduce radial water movements. We therefore conclude that the regulation of radial water movement out of the xylem involves modulation of cGMP levels, water channels and respiration-dependent processes. In addition, we propose that NPs have a critical role to play in radial water movements out of the xylem and speculate that as in vertebrates, NP effects might, at least in part, be mediated via the regulation of guanylate cyclases and water channels. Received 15 June 1998; received after revision 7 August 1998; accepted 26 August 1998     

小肽对幼龄草鱼生长性能的影响

本试验用225尾草鱼分为3组作酪蛋白小肽对幼龄草鱼生长性能的研究。对照组添加0.5％酪蛋白。试验组1和试验组2饵料中分别添加0．5％酶解酪蛋白与0．5％酸解酪蛋白。结果表明：添加0．5％酶解酪蛋白组草鱼其相对生长率、饲料系数、净蛋白沉积率、生长速度均显著高于试验2组和对照组。     

同位素标记结合中性丢失扫描鉴定白蛋白早期糖基化修饰肽段

采用 [13C6] 同位素标记的葡萄糖作为标签,在体外建立非酶糖基化反应模型,并采用MALDI-TOF对模型中的糖基化人血清白蛋白(HSA)进行验证. 以高分辨率的液质联用四级杆飞行时间质谱(HPLC/Q-TOF MS)为分析平台,经过一级质谱(LC/MS)筛选糖基化肽段. 采用target MS/MS模式对筛选出的34条肽段进行分析. 运用蛋白质组学数据分析工具pFind软件对肽段的中性丢失扫描及二级质谱(LC/MS/MS)数据进行分析,最终获得16条早期糖基化修饰肽段的序列及修饰位点信息.      

微生物源抗菌肽表达系统研究进展及改造策略

针对抗菌肽的生物活性、重组表达系统以及分子改造设计进行了回顾总结,提出了抗菌肽研究及技术开发领域目前存在的问题,包括抗菌活性较弱、生物合成效率不高、选择性差等。同时提出分子改造是提高抗菌活性和选择性的有效策略,而优化重组表达系统是提高生物合成效率的关键途径。认为针对抗菌肽的研究和开发,一方面会深化人类对于抗菌肽的结构与抗菌性、选择性、毒性关系的认识,深化对重组表达系统关键步骤及调控机理的认识,具有显著的科学意义;另一方面,由于抗菌肽独特的抗菌机制,不易产生耐药性,对抗菌肽的研发将会大大推动其在药品、食品、化妆品、饲料等领域的应用。