Biomolecular Studies of Biomineralization Proteins: Triplet Motifs

John Spencer EvansMCB 98-167031.技术矿化结构的生物制造，或生物矿化，是一种生物导向的过程，导致复合材料的形成。另一类有趣的与生物矿物有关的蛋白质是与磷灰石和碳酸钙有关的所谓“酸性“蛋白质。这些蛋白质含有大量的天冬氨酸、谷氨酸，在某些情况下还含有磷酸化的丝氨酸残基，可以结合钙离子并启动晶体生长。巧合的是，这些蛋白质也可以立体特异性地结合到形成矿物晶体的暴露表面上，从而促进沿着特定的晶轴生长。但是所有的“酸性”蛋白质都是平等的吗？最近的实验表明，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，这些蛋白质中的重复序列可能代表了Ca（II）识别位点和折叠微结构域的多样性“文库”：通过使用相似或不同的重复序列组合，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。本研究将探讨已知的“酸性”序列重复文库中的相似性和差异性。通过使用多学科的方法，特定的序列重复将检查关于钙（II）的结合，构象变化，晶体生长诱导，和晶体形态匹配。这些结果将提供数据，不仅将促进我们对“酸性”蛋白质结构和功能的理解，而且还为合成“肽模拟物”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生、大学本科生和研究生参与的教育战略;强调独立性、解决问题的能力和团队合作精神.非技术性有许多自然产生的生物基材料--如贝壳和浮游生物外骨骼--它们是由生物体建造的，用于保护和支持。这些生物基材料是独特的，因为它们将联合收割机无机固体（矿物质）与聚合物（蛋白质、多糖）结合。所得到的材料通常非常坚固，并且是由生物体在生物条件下组装的。因此，“生物启发”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，工业和医学创造生物材料。要成功地做到这一点，重要的是要了解蛋白质和多糖如何识别和结合无机固体。这项研究将探讨“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-有机材料的组装的问题。将采用物理技术的组合来研究在“酸性”蛋白质中发现的序列重复的结构。从这些研究中获得的结果将被用来创建一个“酸性”蛋白质的分子“蓝图”，其中可以识别重要和不重要的矿物质分解区域。最终，这些信息将被用于创建“设计师”蛋白质或聚合物，这些蛋白质或聚合物可以在生物灵感材料组装过程中执行特定功能。该研究项目也将作为高中，本科和研究生科学专业培训的教学工具，其中解决问题的能力和跨学科培训将是特色。

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.