Biomolecular Studies of Biomineralization Proteins: Triplet Motifs

约翰·斯宾塞·埃文斯mcb98 -167031。矿化结构的生物制造，或生物矿化，是导致复合材料形成的非生物体导向的过程。一类有趣的生物矿物相关蛋白质是所谓的“酸性”蛋白质，与磷灰石和碳酸钙有关。这些蛋白含有大量的Asp、Glu和某些情况下磷酸化的Ser残基，可以结合Ca （II）离子并引发晶体生长。矛盾的是，这些相同的蛋白质也可能与形成矿物晶体的暴露表面立体特异性结合，从而抑制沿特定晶体轴的生长。但是所有的“酸性”蛋白质都是一样的吗？最近的实验表明，所产生的矿物形态与特定蛋白质中的特定氨基酸序列直接相关。最令人兴奋的是，这些蛋白质中的序列重复可能代表了Ca （II）识别位点和折叠迷你结构域的多样化“文库”：通过使用相似或不同的序列重复组合，给定的“酸性”蛋白质可以“定制”其局部结构以匹配特定的晶体形态或创建特定的晶体形态。本研究将探讨已知“酸性”序列重复文库的异同。通过使用多学科的方法，特定的序列重复将被检查关于Ca （II）结合，构象变化，晶体生长诱导和晶体形态匹配。这些结果将提供一个数据库，不仅将促进我们对“酸性”蛋白质结构和功能的理解，而且还将为合成“拟态肽”和聚合物的创造提供基础，这些聚合物可以产生新的或重要的晶体形态，并最终产生新的复合材料。作为该项目的一部分，将实施一项涉及高中、大学本科生和研究生的教育策略；强调独立、解决问题的能力和团队合作。有许多自然产生的生物材料，如海贝壳和浮游生物的外骨骼，它们是由生物构建的，用于保护和支持。这些生物基材料是独一无二的，因为它们将无机固体（矿物质）与聚合物（蛋白质、多糖）结合在一起。所得到的材料通常非常坚固，并且可以在生物条件下由生物体组装。因此，“仿生”材料提供了一种新的策略——即使用自组装和分子-分子识别作为“建筑技术”——为航空航天、工业和医药创造独特的材料。要成功地做到这一点，了解蛋白质和多糖如何识别和结合无机固体是很重要的。这项研究将探索“酸性”蛋白质，如在海贝壳、骨骼和牙齿中发现的蛋白质，如何参与复合无机-有机材料的组装。物理技术的结合将用于研究在“酸性”蛋白质中发现的序列重复结构。从这些研究中获得的结果将用于创建“酸性”蛋白质的分子“蓝图”，其中可以识别矿物质识别的重要和不重要区域。最终，这些信息将用于创造“设计师”蛋白质或聚合物，这些蛋白质或聚合物可以在仿生材料组装过程中执行特定功能。该研究项目也将作为高中、本科和研究生理科专业的教学工具，以解决问题的能力和跨学科的训练为特色。

John Spencer EvansMCB 98-167031. TechnicalThe biofabrication of mineralized structures, or biomineralization, is anorganism-directed process which leads to composite material formation. Aninteresting class of biomineral-related proteins are the so-called "acidic"proteins found in association with apatites and calcium carbonates. Theseproteins, which contain significant amounts of Asp, Glu, and in some casesphosphorylated Ser residues, can bind Ca (II) ions and initiate crystalgrowth. Paradoxically, these same proteins may also bind stereospecificallyto the exposed surfaces of forming mineral crystals, thereby inhibitinggrowth along specific crystallographic axes. But are all "acidic" proteinscreated equal? Recent experiments have demonstrated that the resultingmineral morphology is directly related to specific amino acid sequences inspecific proteins. What is most exciting is the possibility that sequencerepeats in these proteins could represent a diverse "library" of Ca (II)recognition sites and folding mini-domains: by using similar or differentcombinations of sequence repeats, a given "acidic" protein could "tailor"its local structure to match a specific crystal morphology or create aspecific crystal morphology. This study will investigate the similaritiesand differences within the known "acidic" sequence repeat library. By usinga multidisciplinary approach, specific sequence repeats will be examinedwith regard to Ca (II) binding, conformational change, crystal growthinduction, and crystal morphology matching. These results will provide adatabase that will not only advance our understanding of "acidic" proteinstructure and function, but also provide the basis for the creation ofsynthetic "peptidomimetics" and polymers that can generate novel orimportant crystal morphologies, and, ultimately, novel composite materials.As part of this project, an educational strategy involving participationof high school, college undergraduate, and graduate students will beimplemented; independence, problem-solving skills and team cooperation willbe emphasized.2. Non-technicalThere are a number of naturally-occurring biological-based materials --such as sea shell and plankton exoskeleton -- which are constructed byorganisms for protection and support. These bio-based materials are unique,in that they combine inorganic solids (minerals) with polymers (proteins,polysaccharides). The resulting materials are usually very strong, and, areassembled by organisms under biological conditions. Hence, "bio-inspired"materials offer a new strategy-- namely, using self-assembly and molecule -molecule recognition as "building techniques" -- for creating uniquematerials for aerospace, industry, and medicine. To do this successfully,it is important to understand how proteins and polysaccharides recognizeand bind to inorganic solids. This research will explore the issue of how"acidic" proteins, such as those found in sea shells, bones, and teeth,participate in the assembly of composite inorganic - organic materials. Acombination of physical techniques will be employed to study the structureof sequence repeats found in "acidic" proteins. The results obtained fromthese studies will be used to create a molecular "blueprint" for "acidic"proteins, wherein important and unimportant regions for mineral recognitioncan be identified. Eventually, this information will be used to create"designer" proteins or polymers which can perform specific functions duringbio-inspired material assembly. This research project will also serve as ateaching tool for the training of high school, undergraduate, and graduatescience majors, wherein problem-solving skills and cross-disciplinetraining will be featured.