INTERACTION OF ATP ANALOGUES WITH MYOSIN

将制备各种类型的ATP类似物，以帮助表征 肌肉蛋白质中核苷酸-蛋白质相互作用的性质。一类新 将制备类似物，其利用形成稳定的 氨基甲酰基连接至ATP的2 '（3'）羟基。新的ATP/ADP亲和力 柱将用于制备各种修饰的肌球蛋白亚片段 I（S1）衍生物用于潜在结晶研究。这些 衍生物包括通过两个动力学反应性半胱氨酸交联的S1 和用ATP光亲和衍生物光标记的S1。化学 还原甲基化的S1的性质将通过使用[3 H] H2 CO定义为 有助于制备更均匀的S1制剂的方法， 结合核苷酸的结晶研究。光亲和标记 ATP类似物和扇贝肌球蛋白的研究将探索最近的 发现了差异标记， Ca 2+的调节量。突变轻链将并入 扇贝肌球蛋白，以检验Ca 2+结合的基本假设， 轻链以直接方式影响活性位点。的机理 肌球蛋白活性位点的钒酸盐光裂解和光修饰将 被探索。这项研究应作为其他研究的范例， 钒酸盐促进结合磷酸化的蛋白质的光裂解 印刷受体. 其他研究将制备核糖修饰的ATP重金属衍生物 和GTP（Re络合物）用于单晶X射线研究和ATP 其中Au 11复合物连接到2 '（3'）核糖羟基上， 通过电子显微镜和图像确定粗丝结构 重建研究。

ATP analogues of various types will be prepared to help characterize the nature of nucleotide-protein interactions in muscle proteins. A new class of analogues will be prepared which exploit the ability to form a stable carbamoyl linkage to the 2'(3')hydroxyls of ATP. New ATP/ADP affinity columns will be utilized to prepare variously modified myosin subfragment l (S1) derivatives for potential crystallization studies. These derivatives include S1 cross-linked via two kinetically reactive cysteines and S1 photolabeled with ATP photoaffinity derivatives. The chemical nature of reductively methylated S1 will be defined by use of [3H]H2CO as a means to help prepare more homogeneous S1 preparations for crystallization studies with bound nucleotide. Photoaffinity labeling studies with ATP analogues and scallop myosin will explore the recently discovered differential labeling which occurs in the presence of regulatory amounts of Ca2+. Mutant light chains will be incorporated into scallop myosin to test the hypothesis that Ca2+ binding to the essential light chains affects the active site in a direct manner. The mechanism of vanadate photocleavage and photomodification of myosins active site will be explored. This study should serve as a paradigm for other studies of vanadate promoted photocleavage of proteins which bind phosphorylated substrates. Other studies will prepare ribose-modified heavy metal derivatives of ATP and GTP (Re complexes) for use in single crystal x-ray studies and ATP with Au11 complexes attached to the 2'(3') ribose hydroxyls to be used to define thick filament structure by electron microscopy and image reconstruction studies.