The conformational stabilities of tropomyosins.
The conformational stabilities of tropomyosins.
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原肌球蛋白的构象稳定性。
DOI：
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发表时间：
1976
期刊：
影响因子：
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通讯作者：
E. Woods
中科院分区：
文献类型：
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作者：
E. Woods
研究了7种脊椎动物（包括骨骼肌、心肌和平滑肌）原肌球蛋白和3种无脊椎动物原肌球蛋白对热变性和盐酸胍变性的稳定性。过渡曲线是不连续的，在许多情况下，观察到不同的平台，这表明在中间温度和盐酸胍浓度下存在独特的部分未折叠状态。在大多数情况下，盐酸胍的变性可以通过一个模型来描述，在该模型中，天然状态解折叠成部分解折叠的稳定中间体，然后解折叠成完全变性状态。在此基础上，它是可能的，以估计在水中展开的自由能。结果表明，原肌球蛋白的α-螺旋结构的一部分是只有轻微的稳定性和在水中的这一段的展开的自由能是小于发现的球状蛋白质的值，而另一个片段（或片段）具有稳定性相媲美的球状蛋白质。逐步展开可以解释在原肌球蛋白的卷曲螺旋相互作用。同一物种不同肌肉的原肌球蛋白之间以及物种之间的稳定性存在差异，没有两种原肌球蛋白具有相同的变性特征。无脊椎动物原肌球蛋白的稳定性范围较广，扇贝横纹肌原肌球蛋白较其他几种原肌球蛋白更易变性。未发现原肌球蛋白的稳定性与肌肉调节系统的类型之间存在相关性。脊椎动物和无脊椎动物物种的结果的比较表明，在进化的时间尺度上没有选择的蛋白质的更高或更低的稳定性。
The stability to denaturation by heat and guanidine hydrochloride of seven vertebrate (including skeletal, cardiac and smooth muscle) tropomyosins and three invertebrate tropomyosins was examined. The transition profiles were discontinuous and in many cases distinct plateaux were observed which indicated the presence of unique partially unfolded states at intermediate temperatures and guanidine hydrochloride concentrations. The denaturation by guanidine hydrochloride could be described in the majority of cases by a model in which the native state unfolds to a partially unfolded stable intermediate which then unfolds to the completely denatured state. On this basis it was possible to estimate the free energies of unfolding in water. It was shown that part of the alpha-helical structure of tropomyosin is only marginally stable and the free energy of unfolding in water of this segment is less than values found for globular proteins, whereas another segment (or segments) has a stability comparable to that found for globular proteins. The stepwise unfolding may be explained in terms of the coiled-coil interactions in tropomyosin. Differences in stability were found between tropomyosins from different muscles of the same species as well as between species, no two tropomyosins giving the same denaturation profiles. The invertebrate tropomyosins showed a wider range of stabilities, that from scallop striated muscle being far more easily denatured than all the others. No correlation was found between the stability of tropomyosin and the type of regulatory system of the muscle. A comparison of the results from vertebrate and invertebrate species suggests that there has been no selection for proteins of higher or lower stability during the evolutionary time scale.