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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Search for Electroweak Interactions in Amino Acid Crystals. II. The Salam Hypothesis
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Search for Electroweak Interactions in Amino Acid Crystals. II. The Salam Hypothesis

机译：搜索氨基酸晶体中的电弱相互作用。二。萨拉姆假说

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In 1991, A. Salam proposed that the electroweak interaction might promote tunneling through the potential barrier existing between chiral molecules (i.e., a phase transition at a critical temperature, T_c), which could change the structure of D-amino acids into the reputedly more stable L-form of the enantiomer. A recent report by Wang et al. has presented experimental evidence for such a transition at T_c ≈ 270 ± 1 K in enantiomorphs of L- and D-alanine and -valine crystals using differential scanning calorimetry (DSC), magnetic susceptibility, and Raman spectroscopy. Experimental verification of the Salam prediction has great implications for the origins of specific homochirality in biomolecules, that is, the exclusive use of L-amino acids in proteins. In this contribution, we reexamine these measurements, as well as present measurements of the temperature dependence of X-ray diffraction and C-13 solid-state NMR for alanine. While the DSC measurements show interesting features similar to those reported by Wang et al. at ～270 K, there are significant differences, including the observation that the small feature observed in the DSC experiments becomes even smaller upon recrystallization (i.e., purification). Also, the small change in specific heat at ～270 K is found to be absent in (natural) L-valine. We find no unusual behavior in our additional X-ray diffraction or NMR experiments in this temperature range. We also present arguments against the Salam hypothesis for the molecules under study.
机译：1991年，A。Salam提出，电弱相互作用可能会促进通过手性分子之间存在的势垒的隧穿（即，在临界温度T_c时的相变），这可能会将D-氨基酸的结构改变为更多对映体的稳定的L-形式。 Wang等人的最新报告。通过差示扫描量热法（DSC），磁化率和拉曼光谱法，已经为L-和D-丙氨酸和-缬氨酸晶体的对映体在T_c≈270±1 K处的这种转变提供了实验证据。 Salam预测的实验验证对生物分子中特定手性的起源具有重大意义，即蛋白质中L-氨基酸的专有用途。在这项贡献中，我们重新检查了这些测量值，以及目前对丙氨酸的X射线衍射和C-13固态NMR的温度依赖性的测量值。 DSC测量显示出有趣的功能，类似于Wang等人报道的功能。在〜270 K时，存在显着差异，包括观察到DSC实验中观察到的小特征在重结晶（即纯化）时变得更小。此外，发现（天然）L-缬氨酸中不存在约270 K的比热微小变化。在此温度范围内，我们在其他X射线衍射或NMR实验中未发现异常现象。我们还提出了针对所研究分子的Salam假设的论点。

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