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圆二色光谱、红外光谱法解析羊乳和牛乳β-酪蛋白结构及性质差异 被引量:12
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作者 李萌 王娟 +5 位作者 魏子凯 康佳欣 张玲 tabys dina 刘宁 张爽 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2020年第3期770-776,共7页
羊乳β-酪蛋白比牛乳β-酪蛋白更容易被婴幼儿消化吸收,主要原因是二者结构的不同。目前对牛乳β-酪蛋白结构的研究较多,但对羊乳β-酪蛋白的结构以及羊乳和牛乳β-酪蛋白结构差异的研究还鲜有报道。蛋白质二级结构的信息可由光谱获得,... 羊乳β-酪蛋白比牛乳β-酪蛋白更容易被婴幼儿消化吸收,主要原因是二者结构的不同。目前对牛乳β-酪蛋白结构的研究较多,但对羊乳β-酪蛋白的结构以及羊乳和牛乳β-酪蛋白结构差异的研究还鲜有报道。蛋白质二级结构的信息可由光谱获得,其中圆二色光谱是利用蛋白质分子中具有光学活性的生色基团对左、右平面圆偏振光吸收不同,对蛋白质结构进行表征的方法,可以测定溶液状态下的蛋白质样品,使蛋白质构象更接近其生理状态,而且具有快速简便,对构象变化灵敏等优点;红外光谱则是利用蛋白质分子在振动过程中不同化学键或官能团对红外光吸收频率不同,对蛋白质结构进行表征的方法,可以测定固体状态下的蛋白质样品,具有扫描速度快、分辨率高、可测波长范围广、不易受蛋白质样品的分子大小和外界条件影响等优点。圆二色光谱和红外光谱已被广泛应用于蛋白质构象的研究中,但是结合使用这两种方法分析β-酪蛋白结构的研究还鲜有报道。因此,该研究采用圆二色光谱和红外光谱比较羊乳和牛乳β-酪蛋白的结构特点,并利用分光光度法对二者的巯基含量及溶解性进行了分析,从功能性质方面的不同对两种蛋白结构的差异进行更好的说明。圆二色光谱测得羊乳和牛乳β-酪蛋白二级结构中主要以无规卷曲为主,但羊乳β-酪蛋白的无规卷曲含量(50.2%±0.16%)显著高于牛乳β-酪蛋白(43.8%±0.14%),其有序结构中α-螺旋含量(2.7%±0.21%)、β-折叠含量(15.3%±0.08%)显著低于牛乳β-酪蛋白(4.3%±0.13%, 19.5%±0.12%),β-转角含量分别为31.8%±0.11%和32.4%±0.09%,差异不显著;红外光谱测得羊乳β-酪蛋白二级结构中α-螺旋、β-折叠、β-转角含量分别比牛乳β-酪蛋白低18%~20%, 9%~10%, 0.6%~1%,无规卷曲含量比牛乳β-酪蛋白高17%~19%。对两种蛋白功能性质的研究表明,羊乳β-酪蛋白与牛乳β-酪蛋白表面巯基含量基本一致19~20μmol·g^-1,但羊乳β-酪蛋白总巯基含量[(28.35±0.13)μmol·g^-1]显著低于牛乳β-酪蛋白[(46.72±0.21)μmol·g^-1];羊乳β-酪蛋白与牛乳β-酪蛋白的等电点较为接近(pH为4~5),且在等电点附近前者的溶解性低于后者,而远离等电点时前者溶解性则高于后者。研究结果说明与牛乳β-酪蛋白相比,羊乳β-酪蛋白分子的无序性和柔韧性更高,胶束内部结构更加的柔软疏松。 展开更多
关键词 羊乳 牛乳 Β-酪蛋白 圆二色光谱 红外光谱 二级结构
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Soil and fine root-associated microbial communities are niche dependent and influenced by copper fungicide treatment during tea plant cultivation
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作者 Ali Inayat Mallano Jie Yu +5 位作者 tabys dina Fangdong Li Tiejun Ling Naveed Ahmad Jeffrey Bennetzen Wei Tong 《Horticulture Research》 SCIE CSCD 2023年第3期11-14,共4页
Dear Editor,Fungicide treatment has a profound effect on controlling plant pathogens in modern agriculture,however,it also carries the risk of undesirable outcomes.For decades,scientists have been concerned about the ... Dear Editor,Fungicide treatment has a profound effect on controlling plant pathogens in modern agriculture,however,it also carries the risk of undesirable outcomes.For decades,scientists have been concerned about the harmful impacts of heavy metals like copper(Cu)on crop performance and soil microorganisms.Use of various copper fungicides,like Bordeaux mixture,have been a component of conventional agricultural practices to control fungal and bacterial pathogens,especially in vineyards,tea gardens,or fruit tree orchards[9,10].This treatment increases the accumulation of high levels of Cu in surface soils,and despite the critical role of Cu as an essential trace element in wide biological and metabolic processes,it becomes toxic to plants when applied at high levels[4].The regular application of copper fungicides has also been linked to affecting microbial communities at the levels of diversity[8],population structure[2],abundance,and growth[1,3].Understanding the undesired effects of fungicides on microorganisms’beneficial activities is therefore important for evaluating the hazards associated with the fungicide used in agriculture.Yet,the effects of copper fungicide on full microbial communities remains relatively understudied,especially in tea plants.Thus,we herein explored the inf luence of Bordeaux mixture under different management regimes(raking or without raking leaf litter)on microbial communities of root,bulk soil,and rhizosphere compartments of tea plants planted in a ten-year-old tea garden.We provided insights into the ecological consequences of tea management practices that might help to identify specific fungicide treatment regimens,environmental characteristics,and microbial community members to minimize the negative environmental outcomes and optimize the positive anti-pathogen aspects of fungicide treatment. 展开更多
关键词 SOIL planted COPPER
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