酪蛋白源降血压肽稳定性及其抑制作用机理的研究

酪蛋白源降血压肽经体外胃肠道蛋白酶消化后,其ACE抑制活性仍能保持原来活性的94%.降血压肽与ACE作用前后,其ACE抑制活性和肽谱基本保持不变,证实了酶解乳蛋白源降血压肽是真正的抑制剂类型,不受ACE作用.采用抑制酶解动力学方法,初步探讨降血压肽的抑制作用机理,根据lineweaver-Burk方程,确定酶解酪蛋白源降血压肽是非竞争性抑制类型.     

食品蛋白来源生物活性肽

生物活性肽是蛋白质功能片段经酶解产生具有特殊生理调节功能肽段。该文主要介绍降血压肽、高F值寡肽、酪蛋白磷酸肽、免疫活性肽、清除自由基活性肽等几种国内外广泛关注生物活性肽,并在此基础上对生物活性肽开发进行展望。     

基于模拟酶切的酪蛋白定向酶解探究

用模拟酶切软件peptidecutter提供的39种蛋白酶,对已知序列的酪蛋白进行模拟酶切,以生成的寡肽数量为指标建立酶解肽库,选择适用酶并进行真实条件下的酶解验证,获得最适用酶;以血管紧张素转化酶(ACE)抑制肽的抑制率和酪蛋白磷酸肽(CPP)的氮磷摩尔比来评价ACE抑制肽的活性及CPP的纯度,超滤分离酶解液获得高纯度的ACE抑制肽和CPP。结果表明:胰蛋白酶为最适用酶,超滤后ACE抑制肽的抑制活性及CPP的纯度显著升高(p<0.01),获得了高活性的ACE抑制肽和高纯度的CPP。     

酪蛋白抗氧化肽的胃肠消化稳定性研究

目的:研究酪蛋白抗氧化肽的活性在模拟胃肠消化过程中的稳定性。方法:采用脱脂乳粉为原料提取酪蛋白,经酶解,初步分离得到酪蛋白抗氧化肽。以氧自由基清除能力(ORAC)和2,2′-联氮-双-(3-乙基苯并噻错啉-6-磺酸)(ABTS)自由基清除率为抗氧化指标,采取单因素试验,体外模拟胃肠消化模型研究酪蛋白抗氧化肽的胃肠消化稳定性。结果:酪蛋白抗氧化肽经胃蛋白酶消化后其抗氧化活性显著降低,而在随后的模拟肠消化中抗氧化活性逐渐回升至消化前的水平。在模拟胃消化阶段,胃液pH对于酪蛋白抗氧化肽的抗氧化活性没有显著影响,酶与底物比(E/S)越小,酪蛋白抗氧化肽活性保留得越多;在模拟肠消化阶段,底物浓度越大,其活性恢复得越缓慢。结论:酪蛋白抗氧化肽在模拟胃肠消化过程中的稳定性研究,为日常膳食中生物活性肽的合理搭配提供了理论依据。     

酪蛋白源降胆固醇肽的酶解制备工艺优化

以酪蛋白为原料,采用中性蛋白酶、碱性蛋白酶以及胰蛋白酶对酪蛋白进行水解,确定制备降胆固醇肽的最佳蛋白酶;通过单因素实验和响应面试验,研究水解pH、水解温度、酶与底物比、底物浓度和水解时间对酪蛋白水解度和胆固醇胶束溶解度抑制率的影响,确定最佳水解条件;而后通过超滤和凝胶过滤层析确定降胆固醇肽的初步分离工艺。结果表明:制备酪蛋白源降胆固醇肽的最佳水解工具酶是中性蛋白酶,其最佳酶解条件为反应温度51.3 ℃,酶与底物浓度比6.47%,pH6.34,底物浓度5 g/100 mL,反应时间3.5 h,胆固醇抑制率为58.25%±0.59%;Sephadex G-10分离酪蛋白降胆固醇肽条件为上样浓度80 mg/mL,上样体积2.5 mL,洗脱速度3.5 mL/min;经酶解、超滤及层析后制备的酪蛋白源降胆固醇肽峰1和峰2样品在100 μg/mL的胆固醇溶解度抑制率为24.2%±0.24%和4.3%±0.16%。经酶解制备分离后,获得具有抑制降固醇胶束溶解活性的降胆固醇肽,为降胆固醇肽的开发提供理论研究基础。     

木瓜蛋白酶水解酪蛋白制备降血压肽的工艺优化

目的:以酪蛋白为原料,酶解法制备降血压肽,优化工艺。方法:采用5种不同蛋白酶水解酪蛋白,根据水解产物的血管紧张素转化酶(ACE)体外抑制活性选择蛋白酶。以酶用量、酶解时间、底物浓度3因素作为研究对象,以可溶性蛋白产量、ACE体外抑制活性两参数为评价指标,通过Box-Behnken响应面分析法优化水解工艺。结果:木瓜蛋白酶水解酪蛋白的产物活性最高,因此作为工艺优化用酶。响应面分析法得到的最优工艺条件为:酶用量0.032 g,酶解时间4.53 h,底物浓度0.70%,可溶性蛋白产量1283.71 mg、ACE抑制率为87.23%。结论:Box-Behnken设计可有效优化木瓜蛋白酶水解酪蛋白制备降血压肽工艺,所得工艺稳定可靠。     

酪朊酸钠的酶解及分离分析

利用复合蛋白酶水解酪朊酸钠制备营养性酪蛋白小分子肽，对水解的工艺参数，小分子肽的得率变化及酶解液溶解性进行了系统的研究，并对酶解产物进行了SDS-PAGE电泳实验和氨基酸组成分析。     

酶解牛乳酪蛋白制备ACE抑制肽的研究

目的利用酶技术制备酪蛋白源ACE抑制肽.方法以ACE抑制活性为指标,筛选最佳用酶,优化酶解反应条件,并研究酶解过程中水解度和游离氨基酸含量的变化.结果通过对5种蛋白酶的筛选,最终确定AS1.398中性蛋白酶为水解用酶,制备酪蛋白源ACE抑制肽,其最佳反应条件为pH 7、温度45℃、底物质量分数7.5%、酶用量([E]/[S])5%,水解6 h.在酶解过程中,随着时间的延长,水解度略有增加,而游离氨基酸含量大幅度增加.酪蛋白ACE抑制肽的半抑制浓度(IC50值)为0.68mg/mL.结论牛乳酪蛋白用蛋白酶水解可制备高活性的ACE抑制肽,是获得ACE抑制肽的良好来源.     

专利索引

专利名称用粗奶酪生产酪蛋白活性多肽的工艺专利申请人陆晓民申请(专利)号01115249.4审定公告号1384204本发明涉及一种利用粗奶酪生产酪蛋白活性多肽的工艺,该工艺是将粗奶酪经预处理后,在酪蛋白中加入碱性液对其进行转化改性成为水溶性酪蛋白,然后将水溶性酪蛋白添加至少2种蛋白分解酶分别对其进行酶解,并将酶解液混合得酪蛋白活性多肽;本发明的工艺制备的酪蛋白活性多肽具有多种活性肽,其生理功效混合多种多肽的生理功效、安全无毒、无副作用。专利名称酥油及其生产方法专利申请人冯国强申请(专利)号01107202.4审定公告号1371615酥油用植…     

乳源酪啡肽的研究进展

80年代以来，国外一些学者相继从酪蛋白的酶解产物中发现生物活性肽，证明乳除了具有营养作用外，还具有重要的生理作用。酪啡肽就是其中重要的乳源阿片肽，自从1979年Brantl等人首先从酪蛋白的水解产物中分离到β-酪啡肽-7，对于酪啡肽的制备、分离、纯化等各个方面均有广泛的研究。随着具各种生物活性的短肽的不断发现，其研究和开发日益受到各国学者的关注。     

Technical note: A simple rumen collection device for calves: An adaptation of a manual rumen drenching system

A limited amount of research is available related to the rumen microbiota of calves, yet there has been a recent spike of interest in determining the diversity and development of calf rumen microbial populations. To study the microbial populations of a calf's rumen, a sample of the rumen fluid is needed. One way to take a rumen fluid sample from a calf is by fistulating the animal. This method requires surgery and can be very stressful on a young animal that is trying to adapt to a new environment and has a depressed immune system. Another method that can be used instead of fistulation surgery is a rumen pump. This method requires a tube to be inserted into the rumen through the calf's esophagus. Once inside the rumen, fluid can be pumped out and collected in a few minutes. This method is quick, inexpensive, and does not cause significant stress on the animal. This technical note presents the materials and methodology used to convert a drenching system into a rumen pump and its respective utilization in 2 experiments using dairy bull calves.     

数字印刷系统中的免折页胶订技术

在数字印刷系统的配置中,在不配备折页机的情况下,要想完成单本或多本书籍和文件的成书,就需要寻找出一种特殊的排版、打印、裁切和装订工艺方法来进行处理.采用这种工艺方法,无须使用折页机,只通过切纸机的裁切和过胶装订,就能以最省纸张和最少的纸张印刷次数来完成一本书籍的印刷和装订成书.该技术是数字印刷机应用中一种全新的工艺方式.     

实验用木材切削力测试系统的改造设计

该木材切削力测试系统,用于教学实验中对木材切削力的数据采集、分析及结果保存。工作原理:在对木材进行切削时,切削力作用于压电传感器使传感器发出信号,由放大器将信号放大,最后数据采集卡采集到这些信号,传送给计算机进行检测、分析显示,同时将结果保存。该测试系统适用于测量不同树种、不同条件下的主切削力。     

Molecular and immunological characterization of Mus a 5 allergen from banana fruit

Scope Banana fruit has become an important cause of fruit allergy in the recent years. Among the five registered IUIS allergens, Mus a 1 and Mus a 2 have been characterized in detail. In this study, molecular characterization and evaluation of the allergenic properties of β‐1,3‐glucanase from banana (Musa acuminata), denoted as Mus a 5, were performed Methods and results The gene of Mus a 5 was cloned and sequenced. The obtained cDNA revealed a novel Mus a 5 isoform with an open reading frame encoding a protein of 340 amino acids comprising a putative signal peptide of 28 amino acid residues. By MALDI‐TOF analysis Mus a 5 isolated from banana fruit revealed a molecular mass of 33451±67 Da. Two Mus a 5 isoforms (pI 7.7 and 8.0) were detected by 2D immunoblot with an identical N‐terminal sequence. By mass fingerprint, 76 and 83% of the primary structure was confirmed for the two mature Mus a 5 isoforms, respectively. IgE reactivity to Mus a 5 was found in 74% of patients sensitized to banana fruit. Upregulation of basophil activation markers CD63 and CD203c was achieved with Mus a 5 in a concentration‐dependent manner Conclusion Mus a 5 is a functional allergen and a candidate for the component‐resolved allergy diagnosis of banana allergy.     

自动式汉堡制作机设计

为了减少汉堡制作过程对人工依赖程度高的现状,设计一种自动式汉堡制作机,该自动式汉堡制作机包括机械系统和控制系统两方面。机械系统包括:烤箱、天车系统、储肉柜、机械手、托盘小车、流水线、酱枪、加菜机构;控制系统包括:触摸屏、通讯系统和PLC。控制系统控制机械系统完成加面包、加肉、加汉堡酱、加生菜、加面包5个步骤,实现制作自动化、流水线化,解放劳动力。通过试验验证了自动式汉堡制作机设计的可行性和合理性。     

The Effect of Additives on the Regain of Wool

The changes in pressure, velocity, and energy of a liquid particle emanating from a submerged jet and flowing towards and through a porous medium are predicted. An expression is developed for the volumetric rate of flow of a liquid from a jet entering a porous medium, and the rate is shown to vary less than 20% when the distance from the jet nozzle to the porous medium is doubled. The pressure at any level in a compressible porous medium subjected to an initial uniform flow is determined. The distribution of flow within a layer of wool that is impinged upon by a submerged jet is found to be Gaussian, and photographic evidence shows the spread of the flow as it emerges from the downstream surface.     

食堂餐具回收装置的研究

研发一种食堂餐具回收装置,该装置由机械系统和控制系统组成。机械系统主要包括餐具输送机、旋转电磁式机械臂和处理机三部分。其中,餐具输送机可替代餐厅收餐车收集餐具,并传递至处理机;旋转电磁式机械臂完成餐具从餐具输送机至处理机之间的传递,并倾倒餐具中的残留物;处理机将餐具分类并收集。样机测试结果表明:该装置可替代人力,实现对食堂中不同型号的不锈钢餐具的自动回收、清理和分类,具有良好的实用性和经济性。     

Motion of a thread with a jerk: Theory and experiment

Abstract

We consider the problem of a thread tension with a jerk, originating when reducing an excess. Such a situation develops when lining the weft thread in looms and other textile machines, and also when opening parachutes and aerials. An analytical dependence establishing a connection between the tension of a thread at a conducting end, velocity of application of loading, parameters of the excess, and the length of the joined interval of the thread is obtained. Conditions of applicability of obtained results are defined. Obtained dependences can be used as a basis for resolving a problem of optimization related to the functioning of mechanisms of a weft thread feed for weaver's machine tools.     

氩气回路中杂质CO的在线分析方法

模拟正在建造的中国实验快中子反应堆的气体回路,建立了一个工程上可行的、有多条固定管线和阀门的50 m长快堆覆盖气体放射性氩气取样系统、计算机控制的阀门进样以及氩气中杂质CO的间断性在线分析方法.通过热导检测器出口气体可以排放入通风系统的办法,避免了使用氢火焰离子化检测器以后,放射性气体氩气扩散排放到气体分析实验室产生工作环境的放射性污染问题.其检测限、测量精度和准确度满足了中国实验快堆规定的氩气中杂质CO的分析要求,并达到了美国试验和材料协会(ASTM)在快堆覆盖气体杂质的标准中提出的分析氩气中杂质CO的标准要求.     

Recombinant tropomyosin from Penaeus aztecus (rPen a 1) for measurement of specific immunoglobulin E antibodies relevant in food allergy to crustaceans and other invertebrates

Immunoglobulin E (IgE)-mediated food allergy to crustaceans and mollusks is relatively common and affected individuals typically react to a range of different species. The only known major allergen of shrimp was first described over 20 years ago and later identified as the muscle protein tropomyosin. This protein may be useful as a defined and relevant diagnostic marker for allergic sensitization to invertebrate foods. In order to generate an assay reagent suitable for this purpose, tropomyosin from the shrimp Penaeus aztecus (Pen a 1) was produced as a recombinant protein in Escherichia coli and characterized with respect to IgE antibody binding properties in comparison to natural shrimp tropomyosin. Hexahistidine-tagged rPen a 1 accumulated as a predominantly soluble protein in the E. coli expression host and a two-step chromatographic procedure provided a high yield of pure and homogeneous protein. rPen a 1 displayed chromatographic and folding characteristics similar to those of purified natural shrimp tropomyosin. Serum preincubation with serial protein dilutions revealed similar capacity of recombinant and natural tropomyosin to compete with immobilized shrimp extract for IgE binding. rPen a 1 was further shown to extensively and specifically compete for IgE binding to extracts of other crustacean species, house dust mite and German cockroach.