抗冻蛋白研究进展(英文)

很多越冬的生物会产生抗冻蛋白,这些抗冻蛋白能够吸附到冰晶的表面改变冰晶形态并抑制冰晶的生长.抗冻蛋白在很多生物体内都被发现,不同的抗冻蛋白结构差异非常大.目前的一些研究揭示了几种抗冻蛋白的结构,并提出了抗冻蛋白与冰晶的结合模型,但是还没有一种机制能解释所有抗冻蛋白的作用机理.抗冻蛋白能被广泛的应用到农业、水产业和低温储藏器官、组织和细胞,利用转基因技术提高植物的抗冻性具有重要应用价值.而抗冻蛋白基因的表达调控则有待进一步阐明.     

昆虫抗冻蛋白的研究

抗冻蛋白是具有热滞活性,能结合并抑制冰晶生长和抑制冰的重结晶的一类蛋白质。近几年来,昆虫抗冻蛋白的研究取得了较快的发展,本文通过分析昆虫抗冻蛋白的结构特点、抗冻活性、作用机制,并讨论了抗冻蛋白在食品工业、医学、基因工程方面的应用。结果表明,昆虫抗冻蛋白虽然结构呈多样性,但有很多关键的残基具有保守性,对维持抗冻蛋白结构和功能的完整性发挥着重要的作用;抗冻蛋白是由多基因家簇编码的。其作用机制主要是吸附一抑制机制,抗冻蛋白依靠氢键吸附到冰晶格,抑制冰晶生长;昆虫抗冻蛋白的应用具有很广阔的前景。     

植物抗冻蛋白及抗冻性分子改良

概述了植物抗冻蛋白及其相关基因的研究现状,主要包括植物低温诱导蛋白、具有热滞活性的植物抗冻蛋白及其相关基因的分离、鉴定与表达调控,以及植物抗冻性基因工程研究动态.在此基础上,讨论了该领域研究中的主要问题、发展趋势及近期研究热点.     

甲虫抗冻蛋白热滞活性的二维吸附结合模型

甲虫抗冻蛋白是一种具有规则结构的昆虫抗冻蛋白。在相同浓度条件下,甲虫抗冻蛋白比鱼类抗冻蛋白有更高的热滞活性,目前已成为人们重点研究的一类抗冻蛋白。根据甲虫抗冻蛋白的结构特点及其在冰晶表面的吸附模式,应用二维吸附结合模型计算分析了具有6￣11个β-螺旋(β-helix)结构片段的甲虫抗冻蛋白变体分子,得到了它们的热滞活性随溶液浓度变化的规律,特别是热滞活性与甲虫抗冻蛋白的β-螺旋结构片段数的关系。结果显示,抗冻蛋白在冰晶表面的覆盖度是一个影响其热滞活性的重要因素。     

昆虫对低温的适应——抗冻蛋白研究进展

昆虫抗冻蛋白的研究主要在几种昆虫中展开,到目前为止已有二十多种昆虫抗冻蛋白被分离纯化。本文综述了关于昆虫抗冻蛋白的结构、组成、生物学活性及功能等方面的研究进展。昆虫抗冻蛋白的二级结构为β折叠和β转角,在其特殊的氨基酸序列结构中,半胱氨酸形成的二硫键对稳定其结构和活性起着很重要的作用。影响昆虫抗冻蛋白的因子,如活化蛋白及低分子量溶质的发现开辟了昆虫抗冻蛋白研究的新领域。     

抗冻蛋白应用于水稻悬浮细胞超低温保存的研究

本文将鱼类抗冻蛋白应用于植物细胞的超低温保存。结果表明,在水稻悬浮细胞的两步法保存中,浓度为0.01mg/ml的抗冻蛋白具有特别的负作用,相对高浓度的抗冻蛋白则能减小细胞存活率的波动性。在玻璃化法保存中,浓度为0.2mg/ml的抗冻蛋白能改善保存效果,更高浓度的抗冻蛋白(>5mg/ml)反而会降低保存效果。环境冰晶量、抗冻蛋白浓度、低温保护剂浓度和细胞膜组成等是影响抗冻蛋白使用效果的几大因素。作者在机理分析中认为,一方面,抗冻蛋白能和冰晶作用,抑制重冰晶,防止去玻璃化;另一方面,抗冻蛋白也能和细胞膜作用,诱发膜表面冰晶形成。     

新疆沙冬青抗冻蛋白的提取分离及其热滞活性测定

抗冻蛋白被发现于低温环境下生存的生物体中,它能够吸附在冰晶表面并改变冰晶的生长形态,对于增加植物的抗低温胁迫能力有重要作用。用纤维素DE-52离子柱层析提取分离出了冬季新疆沙冬青(Ammopiptanthus nanus)叶片中的抗冻蛋白(AFPs)。差示扫描量热法(DSC)测定结果表明,当蛋白浓度为20mg/ml时,抗冻蛋白的热滞活性(THA)为0·46℃。经SDS-PAGE电泳分析,此抗冻蛋白的分子量为119·24kDa。     

抗冻蛋白研究进展

南北两极的鱼类生活在低于 0℃ (约- 1 .9℃ )的海水中 ,适应于这种环境 ,其体液内有抗冻物质———抗冻蛋白 (ＡＦＰ)或抗冻糖蛋白 (ＡＦＧＰ) ,以防止体液内冰核的形成与生长。在越冬昆虫体内 ,有活性更高的抗冻蛋白。近年来在耐寒植物中也陆续发现了抗冻蛋白。本文将介绍各类抗冻蛋白的结构和生化性质、功能特性、抗冻作用机制、有关抗冻蛋白基因工程研究及抗冻蛋白的应用研究。1 .抗冻蛋白分子结构及生化特性1 .1　ＡＦＧＰ　　ＡＦＧＰ肽链是由Ａｌａ Ａｌａ Ｔｈｒ三肽单位重复组成 ,苏氨酸残基上接双糖基团 [3 Ｏ ( β Ｄ 半乳糖 ) …     

抗冻蛋白的特性和作用机制

抗冻蛋白是非常热门的研究领域,具有广阔的应用前景。本文结合最新的报道,从抗冻蛋白的多样性、热带活性和改变冰的生长,综述了抗冻蛋白的特性,阐释了抗冻蛋白的作用机制的三种假说：“偶极子—偶极子”假说、氢原子结合模型假说和刚体能量学说。     

黄粉虫不同抗冻蛋白基因家族成员的低温应激表达

黄粉虫Tenebrio molitor L.抗冻蛋白基因家族有多个成员,其氨基酸数量和蛋白结构存在差异。尽管有报道发现冷驯化后这些抗冻蛋白的表达量会升高,但不同家族成员是否存在功能分化尚不清楚。本研究中,检测了冷驯化对低温死亡率的效应和对不同类型的抗冻蛋白家族成员基因表达量的影响。结果表明,冷驯化可以显著降低黄粉虫幼虫的低温死亡率和提高不同类型抗冻蛋白基因的表达量。其中,长的抗冻蛋白和低温死亡率的相关关系最为明显。说明不同的抗冻蛋白家族成员的功能有明显的分化,为进一步理解抗冻蛋白的活性和利用抗冻蛋白提供了新的认识。     

昆虫抗冻蛋白的结构与生物学特性研究

抗冻蛋白(antifreeze proteins AFPs)是一类抑制冰晶生长的蛋白质,它能以非依数性形式降低溶液的冰点而对其熔点影响甚微,因而也被称作热滞蛋白。近几年来对于昆虫抗冻蛋白的研究取得了较快的发展,已有20多种昆虫抗冻蛋白被分离纯化。就昆虫抗冻蛋白的结构特征、生物学特性以及在农业、医学和食品工业等方面的应用进行介绍。     

Salt-induced enhancement of antifreeze protein activity: a salting-out effect

Antifreeze proteins are a structurally diverse group of proteins characterized by their unique ability to cause a separation of the melting- and growth-temperatures of ice. These proteins have evolved independently in different kinds of cold-adapted ectothermic animals, including insects and fish, where they protect against lethal freezing of the body fluids. There is a great variability in the capacity of different kinds of antifreeze proteins to evoke the antifreeze effect, but the basis of these differences is not well understood. This study reports on salt-induced enhancement of the antifreeze activity of an antifreeze protein from the longhorn beetle Rhagium inquisitor (L.). The results imply that antifreeze activity is predetermined by a steady-state distribution of the antifreeze protein between the solution and the ice surface region. The observed salt-induced enhancement of the antifreeze activity compares qualitatively and quantitatively with salt-induced lowering of protein solubility. Thus, salts apparently enhance antifreeze activity by evoking a solubility-induced shift in the distribution pattern of the antifreeze proteins in favour of the ice. These results indicate that the solubility of antifreeze proteins in the solution surrounding the ice crystal is a fundamental physiochemical property in relation to their antifreeze potency.     

Antifreeze proteins in overwintering plants: a tale of two activities

Antifreeze proteins are found in a wide range of overwintering plants where they inhibit the growth and recrystallization of ice that forms in intercellular spaces. Unlike antifreeze proteins found in fish and insects, plant antifreeze proteins have multiple, hydrophilic ice-binding domains. Surprisingly, antifreeze proteins from plants are homologous to pathogenesis-related proteins and also provide protection against psychrophilic pathogens. In winter rye (Secale cereale), antifreeze proteins accumulate in response to cold, short daylength, dehydration and ethylene, but not pathogens. Transferring single genes encoding antifreeze proteins to freezing-sensitive plants lowered their freezing temperatures by approximately 1 degrees C. Genes encoding dual-function plant antifreeze proteins are excellent models for use in evolutionary studies to determine how genes acquire new expression patterns and how proteins acquire new activities.     

昆虫抗冻蛋白: 规则结构适应功能

抗冻蛋白在环境温度低于体液熔点时能够结合到生物体内的冰核表面,通过限制冰核生长和抑制冰晶重结晶而保护有机体免受结冰引起的伤害。与其他生物抗冻蛋白比较,昆虫抗冻蛋白有很强的活性,结构上具有显著特征,如一级结构规律重复,超二级结构为β-螺旋,可与冰晶发生相互作用,具有TXT基序等。该文综述了近年来关于昆虫抗冻蛋白的结构以及分子生物学等方面研究的新进展,讨论了其结构与功能的关系。     

Antifreeze proteins in winter rye

Six antifreeze proteins, which have the unique ability to adsorb onto the surface of ice and inhibit its growth, have been isolated from the apoplast of winter rye leaves where ice forms at subzero temperatures. The rye antifreeze proteins accumulate during cold acclimation and are similar to plant pathogenesis-related proteins, including two endoglucanase-like, two chitinase-like and two thaumatin-like proteins. Immunolocalization of the glucanase-like antifreeze proteins showed that they accumulate in mesophyll cell walls facing intercellular spaces, in pectinaceous regions between adjoining mestome sheath cells, in the secondary cell walls of xylem vessels and in epidermal cell walls. Because the rye antifreeze proteins are located in areas where they could be in contact with ice, they may function as a barrier to the propagation of ice or to inhibit the recrystallization of ice. Antifreeze proteins similar to pathogenesis-related proteins were also found to accumulate in closely-related plants within the Triticum group but not in freezing-tolerant dicotyledonous plants. In winter wheat, the accumulation of antifreeze proteins and the development of freezing tolerance are regulated by chromosome 5. Rye antifreeze proteins may have evolved from pathogenesis-related proteins, but they retain their catalytic activities and may play a dual role in increasing both freezing and disease resistance in overwintering plants.     

The mechanism by which fish antifreeze proteins cause thermal hysteresis

Antifreeze proteins are characterised by their ability to prevent ice from growing upon cooling below the bulk melting point. This displacement of the freezing temperature of ice is limited and at a sufficiently low temperature a rapid ice growth takes place. The separation of the melting and freezing temperature is usually referred to as thermal hysteresis, and the temperature of ice growth is referred to as the hysteresis freezing point. The hysteresis is supposed to be the result of an adsorption of antifreeze proteins to the crystal surface. This causes the ice to grow as convex surface regions between adjacent adsorbed antifreeze proteins, thus lowering the temperature at which the crystal can visibly expand. The model requires that the antifreeze proteins are irreversibly adsorbed onto the ice surface within the hysteresis gap. This presupposition is apparently in conflict with several characteristic features of the phenomenon; the absence of superheating of ice in the presence of antifreeze proteins, the dependence of the hysteresis activity on the concentration of antifreeze proteins and the different capacities of different types of antifreeze proteins to cause thermal hysteresis at equimolar concentrations. In addition, there are structural obstacles that apparently would preclude irreversible adsorption of the antifreeze proteins to the ice surface; the bond strength necessary for irreversible adsorption and the absence of a clearly defined surface to which the antifreeze proteins may adsorb. This article deals with these apparent conflicts between the prevailing theory and the empirical observations. We first review the mechanism of thermal hysteresis with some modifications: we explain the hysteresis as a result of vapour pressure equilibrium between the ice surface and the ambient fluid fraction within the hysteresis gap due to a pressure build-up within the convex growth zones, and the ice growth as the result of an ice surface nucleation event at the hysteresis freezing point. We then go on to summarise the empirical data to show that the dependence of the hysteresis on the concentration of antifreeze proteins arises from an equilibrium exchange of antifreeze proteins between ice and solution at the melting point. This reversible association between antifreeze proteins and the ice is followed by an irreversible adsorption of the antifreeze proteins onto a newly formed crystal plane when the temperature is lowered below the melting point. The formation of the crystal plane is due to a solidification of the interfacial region, and the necessary bond strength is provided by the protein "freezing" to the surface. In essence: the antifreeze proteins are "melted off" the ice at the bulk melting point and "freeze" to the ice as the temperature is reduced to subfreezing temperatures. We explain the different hysteresis activities caused by different types of antifreeze proteins at equimolar concentrations as a consequence of their solubility features during the phase of reversible association between the proteins and the ice, i.e., at the melting point; a low water solubility results in a large fraction of the proteins being associated with the ice at the melting point. This leads to a greater density of irreversibly adsorbed antifreeze proteins at the ice surface when the temperature drops, and thus to a greater hysteresis activity. Reference is also made to observations on insect antifreeze proteins to emphasise the general validity of this approach.     

The mechanism by which fish antifreeze proteins cause thermal hysteresis

Antifreeze proteins are characterised by their ability to prevent ice from growing upon cooling below the bulk melting point. This displacement of the freezing temperature of ice is limited and at a sufficiently low temperature a rapid ice growth takes place. The separation of the melting and freezing temperature is usually referred to as thermal hysteresis, and the temperature of ice growth is referred to as the hysteresis freezing point. The hysteresis is supposed to be the result of an adsorption of antifreeze proteins to the crystal surface. This causes the ice to grow as convex surface regions between adjacent adsorbed antifreeze proteins, thus lowering the temperature at which the crystal can visibly expand. The model requires that the antifreeze proteins are irreversibly adsorbed onto the ice surface within the hysteresis gap. This presupposition is apparently in conflict with several characteristic features of the phenomenon; the absence of superheating of ice in the presence of antifreeze proteins, the dependence of the hysteresis activity on the concentration of antifreeze proteins and the different capacities of different types of antifreeze proteins to cause thermal hysteresis at equimolar concentrations. In addition, there are structural obstacles that apparently would preclude irreversible adsorption of the antifreeze proteins to the ice surface; the bond strength necessary for irreversible adsorption and the absence of a clearly defined surface to which the antifreeze proteins may adsorb. This article deals with these apparent conflicts between the prevailing theory and the empirical observations. We first review the mechanism of thermal hysteresis with some modifications: we explain the hysteresis as a result of vapour pressure equilibrium between the ice surface and the ambient fluid fraction within the hysteresis gap due to a pressure build-up within the convex growth zones, and the ice growth as the result of an ice surface nucleation event at the hysteresis freezing point. We then go on to summarise the empirical data to show that the dependence of the hysteresis on the concentration of antifreeze proteins arises from an equilibrium exchange of antifreeze proteins between ice and solution at the melting point. This reversible association between antifreeze proteins and the ice is followed by an irreversible adsorption of the antifreeze proteins onto a newly formed crystal plane when the temperature is lowered below the melting point. The formation of the crystal plane is due to a solidification of the interfacial region, and the necessary bond strength is provided by the protein “freezing” to the surface. In essence: the antifreeze proteins are “melted off” the ice at the bulk melting point and “freeze” to the ice as the temperature is reduced to subfreezing temperatures. We explain the different hysteresis activities caused by different types of antifreeze proteins at equimolar concentrations as a consequence of their solubility features during the phase of reversible association between the proteins and the ice, i.e., at the melting point; a low water solubility results in a large fraction of the proteins being associated with the ice at the melting point. This leads to a greater density of irreversibly adsorbed antifreeze proteins at the ice surface when the temperature drops, and thus to a greater hysteresis activity. Reference is also made to observations on insect antifreeze proteins to emphasise the general validity of this approach.     

抗冻蛋白研究进展

抗冻蛋白是一类具有热滞效应、冰晶形态效应和重结晶抑制效应的蛋白质。简单介绍了各种抗冻蛋白的生化特征、作用机制及其应用研究 ,并对抗冻蛋白的基因和基因工程研究作了较为系统的综述。