TRIVALENT COPPER AS A PROBABLE INTERMEDIATE IN REACTION CATALYZED BY GALACTOSE OXIDASE
TRIVALENT COPPER AS A PROBABLE INTERMEDIATE IN REACTION CATALYZED BY GALACTOSE OXIDASE
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DOI：
10.1021/ja00418a060
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发表时间：
1976-01-01
影响因子：
15
通讯作者：
HAMILTON, GA
中科院分区：
文献类型：
--
作者：
DYRKACZ, GR;LIBBY, RD;HAMILTON, GA
当用x/2个脉冲之间的短延迟（10-100 ms）确定“Bnmr”谱时，我们只观察到两个等强度的双重态。随着延迟时间超过100 ms，半生成B位点的预期低场单重态逐渐增加，并在8-10 s时达到极限强度（两个双重态相对于4为1）。随着延迟时间的增加，单重态的强度恢复遵循一级动力学，并用于估计X= Cl, Br， I的17 T\= 2.8, 3.9和2.6 s。利用Void18的x， r， x/2脉冲序列法确定了其他B环境下的更短的TVs （B = 10, 14, 8 ms; B = 24, 22, 19 ms, x = Cl, Br， I）。相比之下，I-SB9H9的T′s分别为ax= 34, ub= 21和lb= 40 ms。卤素对轴向B位的弛豫时间有决定性影响。考虑到卤素在lb位置时的T\结果，这似乎更显着，例如对于6-Br-l-SBgHg，取代的硼的T\= 35 ms，而其他位置的T\范围为11至22 ms。我们不认为这种效应与各向异性分子重定向有关。对于对称转子，核在对称轴上的弛豫时间（如I-SB9H9的轴向B位）仅取决于垂直于该轴的运动。19根据转动惯量估计，这种运动将使10-Xl-SBgHg （X=）的相关时间更长（更短的7Ys）
Cl, Br, I) we observe only two doublets of equal intensity when the" Bnmr spectrum is determined with a short delay (10-100 ms) be-tween x/2 pulses. The expected low-field singlet for the hal-ogenated B site gradually grows in as the delay time is in-creased above 100 ms and reaches a limiting intensity (1 relative to 4 for the two doublets) at 8-10 s. 16 The intensity recovery for the singlet as the delay time increases follows first-order kinetics and was used to estimate17 T\= 2.8, 3.9, and 2.6 s for X= Cl, Br, I, respectively. The x, r, x/2 pulse sequence method of Void18 was used to determine the much shorter TVs for the other B environments (ub= 10, 14, 8 ms; and lb= 24, 22, 19 ms for X= Cl, Br, I, respec-tively. For comparison, the T\’s for I-SB9H9 are ax= 34, ub= 21, and lb= 40 ms, respectively. The halogen has a decided effect on the relaxation time of the axial B site. This seems even more remarkable in view of the T\results when the halogen is in a lb position, such as for 6-Br-l-SBgHg where T\= 35 ms for the substituted boron and ranges from 11 to 22 ms for the other positions. We do not feel that this effect is related to anisotropic molecular reorientation. For symmetric rotors, the relaxation time of a nucleus on the symmetry axis (such as the axial B site of I-SB9H9) depends only on motion perpendicular to that axis. 19 As estimated from moments of inertia, such motion would give riseto longer correlation times (shorter 7Ys) for 10-Xl-SBgHg (X=