双酶法在固态白酒生产中的应用

同温α－淀粉酶在清蒸生料的同时,进行精精化,提供在发酵过程中和底物糖化有利条件,加之配合使用 酒精专用糖化酶,可以有效地降低扔槽中的淀粉含量,提高淀粉的利用率及出酒率,保持且提高了原有白酒的风味,工艺简单,在白酒生产中保质保量,提高经济效益,并到推进新工艺,新技术运用和研究及降低消耗,降低成本的作用。     

α－淀粉酶在脲变性过程中构象与活性的变化

本文利用蛋白质内源荧光和紫外吸收变化，研究了细菌α－淀粉酶在脲变性过程中的构象变化，并且与失活过程进行了比较．α－淀粉酶脲变性与失活的动力学数据表明，变性是单相过程过程，而失活是一个双相过程，快相失活的速度常数比变性速度常数至少大一个数量级．     

嗜盐淀粉酶产生菌的筛选鉴定及其酶学性质研究

【目的】筛选分离新的嗜盐淀粉酶产生菌,并对其进行酶学性质研究。【方法】从广西大学奶牛厂的奶牛粪便土壤中分离得到一株能产耐盐淀粉酶的菌株,利用16SrRNA序列对比进行鉴定,经破胞提取胞内总蛋白测定嗜盐淀粉酶酶学性质。【结果】经16SrRNA初步鉴定该菌株为阴沟肠杆菌属(Enterobacter cloacae)。该菌株是非嗜盐菌株,却能产生一种胞内嗜盐淀粉酶。酶学性质研究表明该酶在NaCl终浓度为4mol/L时,酶活力最强,当盐浓度为5.5mol/L时,仍能保持最高酶活的60%;以MOPS-NaCl配制的1%可溶性淀粉溶液为底物时,其最适反应温度为50℃,最适pH值为6.5,pH值在4.5~8.5时均能保持60%以上的相对活力;在35~45℃的温度范围内显示较好的稳定性,相对酶活保持在80%以上,但当温度达到50℃时,酶活力急剧下降;Ca2+浓度对酶活力几乎没有影响;EDTA浓度在10~140mmol/L时酶活力变化不大,大于140mmol/L之后,酶活力逐渐下降。【结论】该菌株是在非嗜盐菌株中发现的具有嗜盐淀粉酶基因的菌株,其嗜盐淀粉酶在高盐环境下具有很高的酶活力。     

枯草杆菌α-淀粉酶在一些色谱体系中的热力学和超热力学研究

通过测定不同温度范围的热力学平衡常数、焓变、熵变、自由能变和补偿温度,研究了枯草杆菌α-淀粉酶在几种色谱介质上的热力学和超热力学。结果表明,在RP-C18反相介质、Zn2+螯合的Sepharose fast-flow亲和介质和WCX-1阳离子交换介质上,当温度分别在13-30和30-50℃范围时,它们的lnKSL分别随绝对温度的倒数线性变化;而在PEG-400和修饰的PEG-400疏水色谱介质上,当温度分别在13-40和13-30℃范围时,它们的lnKSL分别随绝对温度的倒数线性减小,但当温度分别高于40℃和30℃时,它们则随绝对温度的倒数剧烈减小。通过研究不同温度范围的焓变、熵变、自由能变和α-淀粉酶构象变化之间的关系,发现在RP-C18反相和Zn2+螯合的Sepharose fast-flow亲和介质上在30- 50 ℃温度范围内,在WCX-1阳离子交换介质上在13-30 ℃温度范围内,α-淀粉酶的吸附过程由焓变和熵变共同所支配,而在Zn2+螯合的Sepharose fast-flow亲和介质上在13- 30 ℃温度范围内,在WCX-1阳离子交换介质上在30-50 ℃温度范围和在PEG-400 和修饰的PEG-400疏水色谱介质上在13-65 ℃温度范围时,α-淀粉酶的吸附过程仅仅由熵变所控制。最后,通过α-淀粉酶在这些色谱体系中的补偿温度进一步发现,它们的焓变仅仅只能通过它们构象变化所引起的熵变所补偿。     

Modulating Glycoside Hydrolase Activity between Hydrolysis and Transfer Reactions Using an Evolutionary Approach

The proteins within the CAZy glycoside hydrolase family GH13 catalyze the hydrolysis of polysaccharides such as glycogen and starch. Many of these enzymes also perform transglycosylation in various degrees, ranging from secondary to predominant reactions. Identifying structural determinants associated with GH13 family reaction specificity is key to modifying and designing enzymes with increased specificity towards individual reactions for further applications in industrial, chemical, or biomedical fields. This work proposes a computational approach for decoding the determinant structural composition defining the reaction specificity. This method is based on the conservation of coevolving residues in spatial contacts associated with reaction specificity. To evaluate the algorithm, mutants of α-amylase (TmAmyA) and glucanotransferase (TmGTase) from Thermotoga maritima were constructed to modify the reaction specificity. The K98P/D99A/H222Q variant from TmAmyA doubled the transglycosydation/hydrolysis (T/H) ratio while the M279N variant from TmGTase increased the hydrolysis/transglycosidation ratio five-fold. Molecular dynamic simulations of the variants indicated changes in flexibility that can account for the modified T/H ratio. An essential contribution of the presented computational approach is its capacity to identify residues outside of the active center that affect the reaction specificity.     

Spaghetti Enriched with Inulin: Effect of Polymerization Degree on Quality Traits and α-Amylase Inhibition

Inulin is considered a dietary fiber and represents a noteworthy ingredient for food biofortification due to its health effects and its neutral taste. The aim of the work was the evaluation of the quality of pasta produced using whole-meal flours of two ancient Sicilian landraces (Senatore Cappelli-CAP and Timilia—TIM) fortified with two types of inulin (long-chain topinambur inulin IT and low-chain chicory inulin IC), at two different levels of substitution (2 and 4%) to evaluate its possible effect on α-amylase inhibition. The color indices L* and a* were mainly influenced by cultivars, while IT improved the sensory attributes, mainly the elasticity sensation, and influenced less the other sensory attributes: adhesiveness, color, odor, taste, and Over Quality Score for both landraces. The cooking quality was linked mainly to the landrace used, due to the very different gluten matrix of CAP and TIM. IC and IT showed promising α-Amy inhibitory activity with comparable IC₅₀ values of 0.45 ± 0.04 and 0.50 ± 0.06 mg/mL. The enrichment of spaghetti with inulin with an inhibitory effect on α-amylase determined the hypoglycemic properties of pasta, thus lowering the corresponding IC₅₀ value.     

嗜淀粉瘤胃杆菌细胞膜联新支链淀粉酶的鉴定

位于厌氧菌嗜淀粉瘤胃杆菌细胞膜上的一种膜联淀粉酶不能被高盐溶液提取，但能够被4％Triton X-100溶液提取，当其酶保存在4％Triton溶液中，其酶活性比保存在0．01％Triton溶液中稳定．当用支链为底物时，其酶催化的最终产物是藩糖，所以此种膜联淀粉酶应该是新支链淀粉酶。     

Statistical Based Bioprocess Design for Improved Production of Amylase from Halophilic Bacillus sp. H7 Isolated from Marine Water

Amylase (EC 3.2.1.1) enzyme has gained tremendous demand in various industries, including wastewater treatment, bioremediation and nano-biotechnology. This compels the availability of enzyme in greater yields that can be achieved by employing potential amylase-producing cultures and statistical optimization. The use of Plackett–Burman design (PBD) that evaluates various medium components and having two-level factorial designs help to determine the factor and its level to increase the yield of product. In the present work, we are reporting the screening of amylase-producing marine bacterial strain identified as Bacillus sp. H7 by 16S rRNA. The use of two-stage statistical optimization, i.e., PBD and response surface methodology (RSM), using central composite design (CCD) further improved the production of amylase. A 1.31-fold increase in amylase production was evident using a 5.0 L laboratory-scale bioreactor. Statistical optimization gives the exact idea of variables that influence the production of enzymes, and hence, the statistical approach offers the best way to optimize the bioprocess. The high catalytic efficiency (kcat/Km) of amylase from Bacillus sp. H7 on soluble starch was estimated to be 13.73 mL/s/mg.     

Study of Activation and Inhibition of Certain Metal Ions to Amylase Catalyzed Reaction by Microcalorimetry

IntroductionMostcomplicatedreactionshappenedinlivingcrea tures ,amongthemenzymecatalyzedreactionisanimpor tantclass .Itissignificantinboththeoryandpracticetoinvestigateenzymecatalyzedreaction .Therearemanyex perimentalmethodssuchasspectrophotometry ,titrimetry ,isotopemethod ,microcalorimetryandsoon ,inwhichmi crocalorimetryisanewoneduetoitshighsensitivityandaccuracy .Wecanstudythewholeprocessoftheheatef fectusingamicrocalorimeter .Sincetheabsorptionorpro ductionofheatisanintrinsicpropertyofe…     

复合酶在合成洗衣粉中的应用

本文研究了由碱性蛋白酶、淀粉酶、碱性纤维素酶复配而成的复合酶在合成洗衣粉中的应用．结果表明：洗衣粉中添加复合酶,大大提高了其去污力,可同时去除各种类型污垢;在适宜条件下,复合酶与洗衣粉中各成分配伍性良好,并具有较高的酶活稳定性．