固定化条件对葡萄糖酶电极响应性能的影响

用微铂盘电极和交联法制得的酶膜构成葡萄糖酶电极，测定其电流响应特性，研究了酶的固定化条件：酶含量以及载体蛋白和交联剂的用量等，对响应特性的影响。提出较适宜的酶电极制备方法，并检测了所得的电极在不同ｐＨ溶液中的灵敏度，指出其最佳操作条件。     

煤矸石热活化和胶凝化过程中硅铝的配位

为了煤矸石综合利用,用红外谱图和固体核磁共振,研究煤矸石热处理及胶凝化过程中S i和A l的配位变化。研究表明,在煤矸石热活化和水泥制备过程中六配位的铝逐渐转变为四配位的铝。活化煤矸石胶凝化过程中,六配位的铝也逐渐转变为四配位铝,形成铝硅酸盐。水泥胶凝过程中,四配位铝逐渐转变为六配位的铝。通过热活化手段增加煤矸石中四配位铝含量可以提高煤矸石胶凝性能。     

新疆蜗牛酶的研制

以野生蜗牛嗉囊为原料提取蜗牛酶产品,检测所含纤维素酶、淀粉酶的活性,对其蜗牛酶产品进一步测试,结果表明新疆蜗牛酶中的纤维素酶活力为450U/g淀粉酶为405U/g。验证了新疆蜗牛酶中纤维素酶的活力很高。     

Study on screening and cultivation conditions of xylanase-producing alkalophilic bacterial

Xylanisthemajorcomponentofplantcellwallsandthemostabundantpentosaninnature.Xylancontainsβ 1,4 linkedd xylosebackboneswitharabinose,4 O methyl d glucuronicacid,andaceticacidsubstituents[1 ] .Thexylan degradingen zymesincludeendoxylanase(1,4 β d xylanxylanohydrolase;EC3.2 .1.8)and β xylosidase (1,4 β d xylanxylanohydrolase;EC 3.2 .1.37) .xylanasedegradesthexylanbackboneintoxylo bioseandxylooligosaccharides,whileβ xylosidasereleasesxylosylresiduesfromthenonreducingendsofxylooligosaccha…     

Role of Cys221 and Asn116 in the zinc-binding sites of the Aeromonas hydrophila metallo-β-lactamase

The CphA metallo--lactamase produced by Aeromonas hydrophila exhibits two zinc-binding sites. Maximum activity is obtained upon binding of one zinc ion, whereas binding of the second zinc ion results in a drastic decrease in the hydrolytic activity. In this study, we analyzed the role of Asn116 and Cys221, two residues of the active site. These residues were replaced by site-directed mutagenesis and the different mutants were characterized. The C221S and C221A mutants were seriously impaired in their ability to bind the first, catalytic zinc ion and were nearly completely inactive, indicating a major role for Cys221 in the binding of the catalytic metal ion. By contrast, the binding of the second zinc ion was only slightly affected, at least for the C221S mutant. Mutation of Asn116 did not lead to a drastic decrease in the hydrolytic activity, indicating that this residue does not play a key role in the catalytic mechanism. However, the substitution of Asn116 by a Cys or His residue resulted in an approximately fivefold increase in the affinity for the second, inhibitory zinc ion. Together, these data suggested that the first zinc ion is located in the binding site involving the Cys221 and that the second zinc ion binds in the binding site involving Asn116 and, presumably, His118 and His196.Received 3 March 2003; received after revision 4 August 2003; accepted 25 August 2003     

Changes in calpastatin localization and expression during calpain activation: a new mechanism for the regulation of intracellular Ca<Superscript>2+</Superscript>-dependent proteolysis

The amount of calpastatin directly available in cytosol is under the control of [Ca²⁺] and [cyclic AMP]. Prolonged calpain activation also promotes degradation of calpastatin. The fluctuation of calpastatin concentration in cell soluble fraction is accompanied by an initial decrease in calpastatin gene expression, followed by a fivefold increase in its expression when the inhibitor protein is degraded. This process can be conceptualized as a mechanism to regulate calpastatin availability in the cell. This conclusion is supported by the fact that calpain, the other component of this proteolytic system, undergoes changes in its levels of expression in a much more limited manner. Furthermore, this process can be observed both in cells exposed to different natural stimuli, or in other cell lines. Modification of calpastatin gene expression might represent a new tool for the in vivo control of the regulatory machinery required for the modulation of Ca²⁺-dependent proteolysis.Received 18 July 2003; received after revision 3 September 2003; accepted 23 September 2003     

紫外线诱变康宁木霉提高酶活力的研究

通过对康宁木霉菌种的诱变、筛选和固体发酵培养,研究了培养基、培养时间、诱变时间及pH值对诱变菌所产酶的活力的影响．结果表明,康宁木霉经诱变5min,在pH为6．0的玉米秸PDA培养基上培养72h,产生的C1酶和Cx酶的酶活力较高,C1酶的酶活力由73u／g提高到176u／g,增加了2．41倍,Cx酶的酶活力由798u／g提高到2069u／g,增加了2．59倍．     

古耀州瓷着色元素的中子活化分析

运用中子活化分析(NAA)技术,测定耀州瓷釉中29种元素的质量含量,从中选取24种着色元素．通过对比分析,最后确定铁是耀州瓷的着色主元素,证明了考古界“耀州瓷以铁为着色主元素”的说法．     

Fluorescence spectra and enzymatic property of hemoglobin as mimetic peroxidase

0　IntroductionHemoglobin(Hb)isthemajorhemeproteinofredbloodcells(RBCs)andisresponsibleforthetransportofoxygentothetissues.ThefunctionofHbdependsupontheabilityoffer rousironinthehemegrouptobindandreleaseoxygen .Despiteitsprincipalroleasanoxygen carrier,theHbmoleculepossessesdifferentenzymaticactivities[1 ] andamethodwasdevelopedforthedeterminationofHbbasedonitsenzymaticactivityfortheox idationofo phenylenediamine (OPDA)withH2 O2 asanoxi dant[2 ] .Hbasamimeticenzymeofperoxidase ,cancataly…     

Fuzzy cluster analysis of the provenance of ancient Yaozhou porcelain body

The technique of neutron activation analysis (NAA) has been employed to measure the content of 29 kinds of elements in the sample of Yaozhou porcelain bodies,Then a fuzzy cluster analsis has been conducted to the NAA data and a diagram of the dynamic fuzzy cluster analysis has been achived,The results indicate that the batch of ancient Yaozhou porcelain bodies,which were of different overglaze color and were produced by different kilns during a period of over 800 years from the Tang Dynasty (618-907 A.D.) to the Yuan Dyansty(1271-1368 A.D.) ,has shared a stable and concentrated raw material source,Provenances of porcelain bodies from different times ,though having their specific independence ,enjoy a close relationship and are not far from one another,Provenances of porcelain bodies made during the Tang Dynasty and the Five Dynasties (907-960 A.D.)are found to be closer to one another,while those of the Song (960-1279A.D.) and the Jin Dynasty (1115-1234 A.D.)are comparatively concentrated in certain areas and are different from those of the Tang Dynasty .Both the tri-colored glazed pottery made in Yaozhou kilns during the Tang Dynasty and the Yaozhou porcelain bodies of the Tang period are from the same provenance.