...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Kinetics of Melanin Polymerization during Enzymatic and Nonenzymatic Oxidation
【24h】

Kinetics of Melanin Polymerization during Enzymatic and Nonenzymatic Oxidation

机译：酶和非酶氧化过程中黑色素聚合的动力学

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Melanin is an abundant biopigment in the animal kingdom, but its structure remains poorly understood. This is a substantial impediment to understanding the mechanistic origin of its observed functions. Proposed models of melanin structure include aggregates of both linear and macrocyclic units and noncovalently held monomers. Both models are broadly in agreement with current experimental data. To constrain the structural and kinetic models of melanin, experimental data of high resolution with chemical specificity accompanied by atomistic modeling are required. We have addressed this by obtaining electronic absorption, infrared, and ultraviolet resonance Raman (RR) spectra of melanin at several wavelengths of excitation that are sensitive to small changes in structure. From these experiments, we observed kinetics of the formation of different species en route to melanin polymerization. Exclusive chemical signatures of monomer 3,4-dihydroxyphenylalanine (dopa), intermediate dopachrome (DC), and early-time polymer are established through their vibrational bands at 1292, 1670, and 1616 cm(-1) respectively. Direct evidence of reduced heterogeneity of melanin oligomers in tyrosinase-induced formation is provided from experimental measurements of vibrational bandwidths. Models made with density functional theory show that the linear homopolymeric structures of 5,6-dihydroxyindole can account for experimentally observed wavenumbers and broad bandwidth in Raman spectra of dopa-melanin. We capture resonance Raman (RR) signature of DC, the intermediate stabilized by the enzyme tyrosinase, for the first time in an enzyme-assisted melanization reaction using 488 nm excitation wavelength and propose that this wavelength can be used to probe reaction intermediates of melanin formation in solution.
机译：黑色素是动物王国的丰富生物化，但它的结构仍然明白很差。这是理解其观察到的功能的机制来源的重要障碍。提出的黑色素结构模型包括线性和宏环单元的聚集体和非共价保持单体。两种型号广泛地与当前的实验数据一致。为了约束黑色素的结构和动力学模型，需要具有由原子建模的化学特异性的高分辨率高分辨率的实验数据。通过在多个激发波长的近似的激发中获得黑色素的电子吸收，红外和紫外共振拉曼（RR），对其进行敏感的结构而解决了这一点。从这些实验中，我们观察到不同物种形成的动力学，以途径聚糖聚合。单体3,4-二羟基苯基丙氨酸（DOPA），中间多相（DC）和早期聚合物的独占化学签名通过其振动带分别在1292,1670和1616cm（-1）中建立。从振动带宽的实验测量中提供了酪氨酸酶诱导的形成中黑色素寡聚聚糖体的异质性的直接证据。用密度函数理论制造的模型表明，5,6-二羟基吲哚的线性均聚物结构可以考虑通过DOPA-黑色素的实验观察的波数和宽带宽。我们捕获DC的共振拉曼（RR）签名，由酶酪氨酸酶稳定的中间体，首次使用488nm激发波长的酶辅助黑色化反应，并提出该波长可用于探测黑色素形成的反应中间体在解决方案中。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号