MAGNETIC SPIN EFFECTS IN RADICAL ENZYMATIC REACTIONS

自由基酶反应中的磁自旋效应

• 批准号: 2154578
• 负责人: CHARLES Buell GRISSOM
• 金额: $ 16.91万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-04-15 至 1996-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2154578
• 关键词: ammonia lyase; biophysics; carbon carbon lyase; chemical kinetics; cobalamin; cofactor; dopamine beta monooxygenase; electromagnetic radiation; enzyme mechanism; enzyme substrate complex; flash photolysis; free radicals; lipoxygenase; magnetic field; nonradiation isotope effect; phenylalanine 4 monooxygenase; photolysis; radiobiology; robotics; triplet state; ultraviolet spectrometry; unspecific monooxygenase

Our laboratory is using magnetic fields to alter electron-spin intersystem crossing rates in chemical and enzymatic reactions with radical intermediates to prove the existence of radical reaction pathways. Only enzymes with spin-correlated radical intermediates can be affected by a magnetic field. These magnetic fields can be exogenous (a laboratory electromagnet giving rise to a "Magnetic Field Effect") or endogenous (arising from the nuclear magnetic moment of atoms involved in bond homolysis thereby giving rise to a "Magnetic Isotope Effect"). These effects have been demonstrated in chemical systems before, but our research group is the first to study these effects in enzymatic systems postulated to have spin-correlated radical pair intermediates. Our experimental goals are: (1) To determine the magnetic field dependence of the kinetic parameters and isotope effects on the radical enzymes ethanolamine ammonia lyase, diol dehydrase, lipoxygenase, dopamine-B- hydroxylase, peptidylglycine amidating monooxygenase, phenylalanine hydroxylase, and DNA photolyase. In preliminary experiments, we have demonstrated a magnetic field dependence to the rate of ethanolamine ammonia lyase, lipoxygenase, and peptidylglycine amidating monooxygenase. (2) To determine the effect of a magnetic field on the photolysis of vitamin B-12 (cobalamin) cofactors by laser flash photolysis. Although our primary focus is to develop new techniques for studying enzymes with radical intermediates and contribute to a more complete understanding of the role of magnetic spin chemistry in the enzymes with unpaired electrons, our work will also address the growing question of how environmental magnetic fields might interact with biological systems.

我们的实验室正在利用磁场来改变电子自旋系统 在化学和酶促反应中与自由基的交叉率 中间体来证明自由基反应途径的存在。 只 具有自旋相关自由基中间体的酶可以受到 磁场 这些磁场可以是外源性的（实验室 产生“磁场效应”的电磁体）或内源性 （由参与键合的原子的核磁矩引起） 均裂，从而产生“磁同位素效应”）。 这些 以前在化学系统中已经证明了这种效应，但我们的研究 该小组是第一个研究这些影响的酶系统假设 具有自旋相关的自由基对中间体。 我们的实验目标是：（1）确定磁场依赖性 自由基酶的动力学参数和同位素效应 乙醇胺氨裂解酶，二醇脱氢酶，脂氧合酶，多巴胺-B- 羟化酶，肽酰甘氨酸酰胺化单加氧酶，苯丙氨酸 羟化酶和DNA光裂合酶。 在初步实验中，我们有 证明了磁场依赖于乙醇胺的速率 氨裂解酶、脂氧合酶和肽酰甘氨酸酰胺化单加氧酶。 (2)为了确定磁场对光解的影响， 维生素B-12（钴胺素）辅因子的激光闪光光解。 虽然我们的主要重点是开发新的技术， 酶与自由基中间体，并有助于更完整的 理解磁自旋化学在酶中的作用， 我们的工作也将解决日益增长的问题， 环境磁场可能与生物系统相互作用。