AB INITIO STRUCTURE DETERMINATION OF XYLAN ESTERASE

木聚糖酯酶从头开始结构测定

• 批准号: 6309533
• 负责人: STEVEN E EALICK
• 金额: $ 2.43万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-12-01 至 2000-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6309533
• 关键词: biological products; biomedical resource; computers; structural biology; technology /technique

We are using the SP parallel supercomputer to determine the X-ray crystal structure of acetyl xylan esterase (AXE) using a new ab initio phasing procedure. The procedure is based on the joint probability distribution between measured X-ray intensities and their unknown phases. The overall problem is expressed in terms of the global, constrained minimum for a function in which the unknown phases are variables. The procedure has been implemented as a computer program called Shake-and-Bake (SnB) which has recently been tested on the IBM SP2 at Cornell. Although direct phasing methods have been routinely used to solve structures with 100 or fewer atoms, protein structures are usually determine by other methods. Recently, however, the structure of androctonus scorpion toxin II, which contains 620 non-hydrogen atoms was routinely solved using the SnB program. AXE is an enzyme containing 1500 non-hydrogen atoms and its structure is currently unknown. X-ray intensity data for AXE were measured to 0.9 resolution at the Cornell High Energy Synchrotron Source (CHESS). Successful application of SnB in the structure determination of AXE will represent an important advance in the field of macromolecular crystallography. Proof that large protein structures can be determined from intensity data alone, without the use of heavy-atom derivatives, will pave the way for further development and optimization of the computer algorithms. When this happens, many new protein structures may be determined using these methods which will require days rather than months (or years) to produce results.

我们正在使用 SP 并行超级计算机来确定 X 射线 使用新的从头算法测定乙酰木聚糖酯酶 (AXE) 的晶体结构 分阶段程序。 该过程基于联合概率 测量的 X 射线强度与其未知强度之间的分布 阶段。 总体问题以全局的形式表达， 未知相为函数的约束最小值 变量。 该过程已作为计算机程序实现 称为 Shake-and-Bake (SnB)，最近已在 IBM 上进行了测试 康奈尔大学 SP2。 尽管直接定相方法已成为常规方法 用于求解具有 100 个或更少原子的结构、蛋白质结构 通常通过其他方法确定。 然而最近， 第620章 蝎子毒素II的结构 非氢原子通常使用 SnB 程序求解。 AX 是 一种含有1500个非氢原子的酶，其结构是 目前未知。 AX 的 X 射线强度数据测量为 0.9 康奈尔高能同步加速器源 (CHESS) 的分辨率。 SnB在AX结构测定中的成功应用 将代表高分子领域的重要进展 晶体学。 证明大型蛋白质结构可以 仅根据强度数据确定，不使用重原子 衍生品，将为进一步发展铺平道路 计算机算法的优化。 当这种情况发生时，许多新 可以使用这些方法确定蛋白质结构，这将 需要几天而不是几个月（或几年）才能产生结果。