果菠萝蛋白酶在有机溶剂中的变性与失活动力学的研究

测得果菠萝蛋白酶是由单亚基组成,分子量约为30k,pl为4.6,每个酶分子含一个游离疏基和二个硫硫键,甲醇、乙醇、乙二醇对酶活力有明显的抑制作用,甲醇、乙醇表现为非竞争性,乙二醇为竞争性,其抑制常数分别为:20％、16.5％和11％。在有机溶剂作用下,监测荧光(332nm)强度随时间的变化过程,作为变性的指标,测定酶在不同浓度有机溶剂中的变性动力学,并按邹氏法测定酶的失活动力学,对酶构象及催化活力关系进行比较,酶的失活速度大于变性速度,说明酶活性中心处于对有机溶剂较敏感的区域,酶的变性与失活过程均可分为快、慢两相的一级反应,这意味着可能存在着部分活力的中间态。     

汾酒大曲根霉糖化酶的研究——Ⅳ在有机溶剂中的动力学与热力学特征

我们用一株根霉(Rhizopus sp.)所产的葡萄糖淀粉酶(Glucoamylase,EC3.2.1.3)经本实验室所创的分离纯化法进行纯化,达到电泳纯。用该酶研究其在有机溶剂乙二醇,甲醇,1,4-二氧六环和四氢呋喃等存在下的热力学和动力学特征,并与相应的溶液酶作比较,讨论了溶剂酶(有机溶剂存在下的酶)和溶液酶在催化活性及分子构象方面的特征。     

长毛对虾磷酸酯酶的研究

从长毛对虾(Penaeuspenicillatus)头胸部、肌肉分别提取纯化碱性磷酸酶ALPase(EC．3．1．3．1)和酸性磷酸酶ACPase(EC．3．1．3．2),经快速蛋白液相色谱(FPLC)检测AL-Pase,聚丙烯酰胺凝胶电泳以及等电聚焦电泳检测ACPase,得到单一纯酶．ALPase紫外特征吸收峰在278nm处,荧光激发峰在282nm处,发射光谱特征峰在340nm处．ACPase在280nm处有紫外吸收特征峰,荧光激发峰在284nm处,发射峰在347nm处．分别测定了酶的相对分子质量、亚基数、氨基酸组成、等电点、酶水解对硝基苯磷酸二钠(pNPP)的最适温度,最适pH,米氏常数Km值,金属离子Mg2+、Cu2+、Hg2+,有机溶剂甲醇、乙醇、乙二醇,化学修饰剂BrAe、NBS、pCMB等以及蛋白质变性剂胍、脲等对酶活力的影响．比较研究健康虾和病虾ACPase酶活力及酶动力学特征常数的变化(健康虾酶Km=0．08mmol／L,病虾酶Km=0．143mmol／L)．病虾酶Km值明显增大,表现对底物亲和力下降．活化能明显增大(健康虾酶41．03kJ     

脲对果菠萝蛋白酶的变性与失活动力学

以脲为变性剂,以荧光光谱为监测手段,对果菠萝蛋白酶(Fruit bromelain)的分子构象变化进行研究,酶的荧光强度随脲浓度增大而递增,发射峰出现红移。荧光偏振在 230～240 nm及 260～290 nm 出现二个负峰,后者较为显著,并随脲浓度增大而加剧。脲对酶水解N-苄氧羰酰 L-赖氨酸对硝基酚酯(CBZ-Lys·pNP)活力的影响,表现为非竞争性抑制类型;比较脲对游离酶(E)及结合酶(ES)的失活速度常数。结果二者相等,底物不表现保护作用。测定酶在不同浓度脲中的变性速度常数和失活速度常数,比较了酶的构象变化及催化活力的关系,酶的失活速度常数比变性速度约大6～16倍。说明酶活性中心对脲的敏感性,酶活力的表现很大程度上依赖于酶构象的稳定性和完整性。     

新型苊并吡嗪类高灵敏度极性探针

以苊醌为原料,经溴化、环构化和芳香亲核取代反应合成了一种新型的以苊并吡嗪为母体的极性荧光探针3-正丁胺基-苊并吡嗪-8,9二腈(A)。探针A的荧光强度随着溶剂极性的增加显著降低,从四氯化碳(Φf=0.364 2)到乙腈(Φf=0.000 6)荧光量子产率减弱超过600倍,从四氯化碳(533nm)到N,N-二甲基甲酰胺(651nm)最大发射波长红移了118nm。利用探针A对极性敏感来检测有机溶剂中的水含量,建立了一种新的四氢呋喃和1,4-二氧六环中水含量荧光分析方法,最低检测限分别为0.019%和0.0076%。     

十二烷基硫酸钠对猕猴桃蛋白酶的变性作用

应用光谱法观测酶的结构变化,紫外差光谱显示在233nm有一较明显的差吸收负峰,在286nm、300nm左右有不大的负峰和在265nm的正峰;荧光谱显示327nm的相对荧光强度随SDS浓度的增高而递减;发射峰位置红移,酶受SDS>4.1mmol/1作用1h,可引起310nm新荧光发射肩。动力学资料表明,SDS对酶的变性过程为一级反应;酶的失活分快慢相,呈现二个一级反应,同时测定在SDS作用下actinidin的变性与失活速度,表明酶的失活速度大于变性速度,似可认为低浓度SDS能使结构域相错开,从而敏感地改变活性部位的微区结构,导致酶快速失活,提高SDS浓度则使酶的结构域发生构象变化,引起光谱法所显示的特征。     

乙醇对鲍鱼碱性磷酸酶活力与构象的影响

以乙醇为效应物研究对鲍鱼碱性磷酸酶(ALP)活力影响的结果表明．酶的剩余活力随着乙醇浓度增大而迅速下降，乙醇浓度40％可使酶活力完全丧失．说明乙醇对鲍鱼ALP有明显的失活作用，JG50为13％．含较低浓度乙醇(30％)的失活过程是可逆的反应．测定乙醇对酶的失活作用机理．结果表明乙醇对鲍鱼ALP的失活作用是非竞争性机制，说明底物存在不影响乙醇对酶的失活作用．应用荧光光谱、紫外吸收光谱研究鲍鱼ALP经乙醇微扰后的分子构象变化，发现乙醇对酶分子构象有显的影响，酶的内源荧光强度随乙醇浓度增大而增强．荧光发射峰逐渐发生红移．紫外吸收光谱在276nm吸收峰随乙醇浓度增大而增强．这些结果表明．酶蛋白分子中的生色基团残基的微环境发生变化．     

中华猕猴桃蛋白酶在乙醇溶液中的分子折叠

研究了中华猕猴桃蛋白酶在不同浓度（Ｖ：Ｖ）乙醇存在下的内源荧光发射光谱、紫外差光谱、圆二色光谱（ＣＤ谱）及傅立叶变换红外光谱的变化，并测定了相应的活力变化，当乙醇浓度低于３０％时，酶的荧光强度无明显变化，而乙醇浓度大于３０％时，则酶荧光强度增大，且峰位略红移。在乙醇溶液中，酶的紫外差光谱在２２５～２３５ｎｍ内出现正峰，峰强度随乙醇浓度的增高基本表现为逐渐增大，峰位也逐渐蓝移。ＣＤ谱及红外光谱的测定结果表明低浓度乙醇中酶分子有序二级结构的减少及高浓度乙醇中β－折叠含量的增加．随乙醇浓度的增加．酶的活力表现为逐渐降低，且乙醇对酶的失活作用类似于竞争性抑制。     

有机溶剂对南美白对虾N-乙酰-β-D-氨基葡萄糖苷酶活力的影响

研究了几种有机溶剂对南美白对虾（Penaeus vannamei）N-乙酰-β-D-氨基葡萄糖苷酶（NAGase）活力的影响．结果表明：甲醇、乙醇、正丙醇、正丁醇、乙二醇和丙三醇对NAGase的作用均表现为低浓度时对酶有激活作用，随着浓度的升高，激活作用减弱并速转为抑制作用；二甲亚砜和二氧六环对酶的抑制作用呈现明显的浓度效应，随浓度增大酶活力迅速下降．进一步研究二甲亚砜的抑制作用动力学，结果表明：二甲亚砜对酶的抑制作用是一种可逆过程，抑制机理表现为混合型抑制类型，抑制常数K1=0．27mol／L，KB=2．05mol／L．     

水-有机溶剂混合体系中辣根过氧化物酶的催化反应

运用分光光度法和傅立叶变换红外光谱研究了辣根过氧化物酶（HRP）在甲醇、乙腈和二氧六环与水互溶溶剂体系中的性质变化,研究结果显示不同种类和含量的有机溶剂都使HRP有不同程度的失活,HRP在有机溶剂中的米氏常数（Km）增大了,但HRP的活性点结构没有遭到破坏,只是将活性部位从一个包埋于酶分子内部的、疏水的环境暴露于极性的有机溶剂中．傅立叶变换红外光谱研究结果显示在有机溶剂中酶分子的二级结构发生了变化,推测可能是酶在有机溶剂中的活性降低的原因．     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.