植物甜蛋白Thaumatin研究进展

甜蛋白自 2 0世纪 70年代发现以来 ,一直倍受人们关注 ,而源于自然的Thaumatin是植物甜蛋白中的一种 ,它具有低热量、高甜度、安全无毒 ,并可降解为人体所需的氨基酸等多种优点 ,是一种新型甜味剂。在物质文化生活日益丰富的今天 ,人们越来越重视饮食的科学性 ,吃饱的同时更加关注所摄入食品的品质 ,无疑具多功能的非糖类物质 Thaumatin就是人们所需求的理想食品。因此 ,Thaumatin成为热门研究领域之一也就不足为怪了。1 　植物甜蛋白研究概况迄今为止 ,人们从多种植物中发现并分离出 7种甜味蛋白 [1 ]。更确切地说 ,其中 5种( Thaumatin,…     

植物甜蛋白的研究进展

本文简要介绍了近年来在植物中发现的几种甜味蛋白质的分子结构及其化学性质。讨论了它们在结构上的相关性及可能的甜味机制,并对甜蛋白在食品工业及植物改良方面的应用进行了展望。     

超甜蛋白的基因工程及开发研究进展

甜蛋白是一类高甜度、低热量、多功能的新型超级甜味剂,应用前景广阔。由于它们存在于几种稀有的植物中,产地偏僻,产量低,提取困难,因而不能发挥它们的使用价值。运用基因工程等高新生物技术,将甜蛋白基因克到微生物细胞中,构建产生甜蛋白基因工程菌株,将为工厂化发酵生产甜蛋白开辟一条快速有效的新途径。     

香蕉类甜蛋白基因MaTLP1的克隆与表达分析

在香蕉EST文库中,通过RACE技术克隆到1个香蕉类甜蛋白基因的全长序列。该序列最大开放阅读框942 bp,编码313个氨基酸。Blast分析发现,它与其他类甜蛋白相似度为56.10%,含有类甜蛋白（TLPs）特有的保守结构域,命名为MaTLP1。系统进化树表明,MaTLP1基因编码蛋白与海枣的亲缘关系较近,与香蕉的进化模式相似。组织特异性分析表明,MaTLP1在根、球茎、假茎中的表达量高,叶中较弱,花和果实中微量表达。实时荧光定量PCR分析显示,在抗病香蕉品种中,接种尖孢镰刀菌古巴专化型(Fusarium oxysporum f.sp.cubense,Foc)枯萎病菌后MaTLP1基因上调表达,在感病香蕉品种接菌2 d后MaTLP1基因受到抑制,虽然在接菌4 d 后上调表达,但是相对于抗病品种上调较小。研究表明,MaTLP1基因可能在香蕉抗枯萎病的过程中起作用。     

甜蛋白与抗虫蛋白

在植物中发现有极甜的蛋白质。植物中也有抗虫的蛋白质,其中一类抗虫蛋白与甜蛋白在结构上极为相似。介绍了它们的研究现状和广泛的应用前景。     

叶绿体类囊体腔蛋白功能研究进展

【目的】类囊体是叶绿体光合作用中光反应进行的重要场所。类囊体腔是由类囊体膜包围形成的一个狭小空间。在类囊体腔中存在多种不同的蛋白家族,包括高叶绿素荧光(high chlorophyll fluorescence, HCF)蛋白、亲免蛋白、放氧复合物(oxygen-evolving complex, OEC)蛋白、PsbP类蛋白等,它们对植物的光合作用、核酸代谢以及氧化还原反应等都起着重要作用。【评论】文章分类综述了参与光合作用调控的类囊体腔蛋白在光系统组装、植物生长发育调节和高光逆境响应等生理活动中发挥的重要作用。【展望】文章可为未来研究类囊体腔蛋白的生理功能提供理论参考。     

植物甜蛋白brazzein基因的克隆与表达

根据大肠杆菌偏爱的密码子,利用PCR技术体外人工合成brazzein cDNA序列,并将其克隆至原核高效表达载体pET30a( )中。重组载体pET30a( )-brazzein转化至大肠杆菌BL21(DE3)中,经IPTG诱导后,SDS-PAGE结果证明pET30a( )-brazzein在大肠杆菌中获得高效表达,目的蛋白占总菌体蛋白25％左右。     

单链莫内甜蛋白基因的合成及其植物表达载体的构建

目的:合成单链莫内甜蛋白基因,构建其植物表达载体。方法与结果:根据已报道的单链莫内甜蛋白的氨基酸序列及甜味机理,重新设计合成了全长294bp的莫内甜蛋白基因,其中单链莫内甜蛋白氨基酸序列中的Asp69(原AspA16)突变为Asn。利用DNA重组技术,将莫内甜蛋白基因克隆到植物表达载体pBl221中,构建了莫内甜蛋白基因的植物表达载体pBI221-monellin。结论:构建了莫内甜蛋白基因的植物表达载体,为转化园艺植物以改善其口感奠定了基础。     

奇异果甜蛋白及其基因工程

奇异果甜蛋白(thaumatin)是迄今为止最甜的物质之一,对其研究具有很重要的意义。奇异果甜蛋白的生化性质基本清楚,基因序列和氨基酸序列都已测定。它的甜味可能是由奇异果甜蛋白上特定基团和受体结合引起的。对奇异果甜蛋白的生理功能知之甚少。近二十年来,在奇异果甜蛋白的基因工程上取得了一定进展,但仍然存在许多困难。 Abstract:Thaumatin is one of the sweetest substances known to date,it is important to study the thaumatin.The biochemical properties of thaumatin have been clarified clearly.Thaumatin had been isolated and sequenced.The mechanism of the sweetness of thaumatin may be due to the combination of some special groups and the receptors.The exact function of thaumatin is still not clear.Although gene engineering of thaumatin has been carried out for 20 years,there are still some difficulties to be solved for using in the market.     

植物病程相关蛋白及其在烟草中的研究进展

植物在受到病原物侵染时,会产生一系列抗性反应,病程相关蛋白是其中参与抗病性的重要物质,能够被病原物诱导产生并在植物体内积累,对于诱导植物系统抗性,阻止病原物侵染具有重要作用。对植物病程相关蛋白的性质、诱导因素、分类和功能进行综述,并概述病程相关蛋白与烟草系统抗性的紧密联系以及烟草病程相关蛋白基因在增强系统抗性中的应用,为烟草抗病育种和病虫害防治提供了理论。     

Purification and characterization of a wound-inducible thaumatin-like protein from the latex of Carica papaya

A 22.137 kDa protein constituent of fresh latex was isolated both from the latex of regularly damaged papaya trees and from a commercially available papain preparation. The protein was purified up to apparent homogeneity and was shown to be absent in the latex of papaya trees that had never been previously mechanically injured. This suggests that the protein belongs to pathogenesis-related protein family, as expected for several other protein constituents of papaya latex. The protein was identified as a thaumatin-like protein (class 5 of the pathogenesis-related proteins) on the basis of its partial amino acid sequence. By sequence analysis of the Carica genome, three different forms of thaumatin-like protein were identified, where the latex constituent belongs to a well-known form, allowing the molecular modeling of its spatial structure. The papaya latex thaumatin-like protein was further characterized. The protein appears to be stable in the pH interval from 2 to 10 and resistant to chemical denaturation by guanidium chloride, with a of 15.2 kcal/mol and to proteolysis by the four papaya cysteine proteinases. The physiological role of this protein is discussed.     

Different Structural Behaviors Evidenced in Thaumatin-Like Proteins: A Spectroscopic Study

Three proteins belonging to the thaumatin-like proteins family were compared in this study from a structural point of view: zeamatin, a new recently isolated PR-5 from Cassia didymobotrya and the commercial sweet-thaumatin. The former two proteins possess antifungal activities while commercial thaumatin is well known to be a natural sweetener. Intrinsic fluorescence studies have evidenced that the three proteins behave differently in unfolding experiments showing different structural rigidity. All the three proteins are more stable at slight acidic buffers, but sweet-thaumatin has a major tendency to destructurate itself. Similar observations were made from circular dichroism studies where a structural dependence relationship from the pH and the solvent used confirmed a hierarchic scale of stability for the three proteins. These structural differences should be considered to be significant for a functional role.     

植物Rab蛋白的研究进展

Rab蛋白是小G蛋白超级家族中的成员之一。通过Rab蛋白氨基酸序列的系统进化分析表明,植物Rab家族又可分为8个亚家族,分别为RabA、RabB、RabC、RabD、RabE、RabF、RabG和RabH。Rab蛋白一般位于胞内特异膜系统的胞质面,它们是小泡运输的关键调节因子。Rab蛋白有非常保守的结构域,同时又具有功能多样性,它们在细胞分化、顶端优势、花粉管发育、根瘤形成以及生物和非生物胁迫反应中均起着非常重要的作用。该文对近年来国内外有关植物Rab蛋白的结构特点及其多样性功能的研究进展进行综述。     

精子膜表面蛋白的研究进展

动物的精子是一类结构和功能都十分特化的细胞,其膜表面存在多种糖蛋白或糖复合物,它们与精卵识别、结合以及质膜融合等受精活动密切相关,同时,作为精子膜抗原,在免疫避孕和免疫不育的治疗中具有广阔的应用前景。本文扼要概述了精子膜蛋白的研究进展。     

Accumulation of Pathogenesis-Related Proteins in Tobacco Leaves Irradiated with UV-B

Nicotiana tabacum L. (cv. Petit Havana SR1) were grown under ultraviolet-B (UV-B, 290–320 nm) irradiation, and soluble proteins were extracted from the leaves. Two-dimensional electrophoresis revealed that a minimum of 12 polypeptides were induced by UV-B. Polypeptides which were so abundant as to be detectable by Coomassie brilliant blue staining were then subjected to N-terminal amino acid sequence analyses. Two of the polypeptides were identified as a 23 kDa protein of PS II and 6 as a pathogenesis-related protein 5 (PR-5). Immunoblotting demonstrated that other PR proteins, PR-1 and PR-3 were also induced by UV-B. Salicylic acid (SA), which is an important component of signal transduction that leads to the expression of PR proteins and exhibition of acquired resistance to pathogens, increased in response to exposure to UV-B. In addition, the activity of phenylalanine ammonialyase, which catalyzes the synthesis from phenylalanine of trans-cinnamic acid, the endogenous precursor of SA, was transiently increased by UV-B irradiation. These results suggest that UV-B activates the signal transduction pathway, which is a common step in pathogen infection. Received 8 May 2000/ Accepted in revised form 29 August 2000     

海洋生物蛋白资源酶解利用研究进展

海洋生物蛋白资源是海洋生物资源的重要组成部分,对其进行高值化加工利用,是海洋生物技术研究的重要内容。对海洋生物蛋白资源酶解利用的研究进展进行了综述。     

囊泡转运蛋白SM蛋白家族的研究进展

真核细胞中含有多种不同功能的转运囊泡。虽然转运途径和携带物质各异,但细胞转运的基本分子机制却呈现出高度相似性和保守性。大多数转运途径都需要一种SNARE（Soluble NSF Attachment Protein Receptor）蛋白质复合体介导转运膜泡与靶膜的融合。同时,另一个蛋白家族,Secl／Muncl8蛋白（SM蛋白）也在囊泡运输中发挥重要作用。但是相比于对SNARE蛋白的认识的一致性,在不同的研究中SM蛋白的功能及其与SNARE复合体的相互作用方式却不尽相同。以下综述近年来有关SM蛋白结构和功能的研究进展,并归纳SM蛋白分子的作用机制、功能以及应用。     

Small GTP-binding Proteins and their Functions in Plants

Small GTP-binding proteins exist in eukaryotes from yeast to animals to plants and constitute a superfamily whose members function as molecular switches that cycle between “active” and “inactive” states. They regulate a wide variety of cell functions such as signal transduction, cell proliferation, cytoskeletal organization, intracellular membrane trafficking, and gene expression. In yeast and animals, this superfamily is structurally classified into at least five families: the Ras, Rho, Rab, Arf/Sar1, and Ran families. However, plants contain Rab, Rho, Arf, and Ran homologs, but no Ras. Small GTP-binding proteins have become an intensively studied group of regulators not only in yeast and animals but also in plants in recent years. In this article we briefly review the class and structure of small GTP-binding proteins. Their working modes and functions in animals and yeast are listed, and the functions of individual members of these families in plants are discussed, with the emphasis on the recently revealed plant-specific roles of these proteins, including their cross-talk with plant hormones and other signals, regulation of organogenesis (leaf, root, and embryo), polar growth, cell division, and involvement in various stress and defense responses.     

无序蛋白质的判定及其结构、功能和进化特征

固有无序蛋白质(intrinsically disordered proteins,IDPs)是天然条件下自身不能折叠为明确唯一的空间结构,却具有生物学功能的一类新发现的蛋白质.这类蛋白质的发现是对传统的"结构-功能"关系认识模式的挑战.本文首先总结了无序蛋白质的实验鉴定手段、预测方法、数据库;并介绍了无序蛋白质结构(包括一级结构、二级结构、结构域无序性及变构效应)和功能特征;然后重点总结了无序蛋白质在进化角度研究的进展,包括无序区域产生的进化机制、进化速率,蛋白无序性的进化在蛋白质功能进化及生物学复杂性增加等方面的重要作用;最后展望了无序蛋白质在医药方面的应用前景.本文对于深入认识无序蛋白质的形成机制、结构和功能特征及其潜在的临床应用前景具有重要意义.