生物大分子波谱学原理 TOCSY 0.6 0.4 250 FIGURE 6. 44 Variation of cross-peak intensity as a function of isotropic mixing time for an isoleucine spin system. (a)Cross-peak intensity for transfer from the ho spin with the h spin removed and(b)cross- peak intensity for magnetization transfer from the ' H spin. The curves for the destination spins are ( Ho,(--)H, (-.)HY,(.H2, and(----)'H. The transfer functions were calculated using the following coupling constants: J 10.0 Hz and JH HA=12 Hz. Vicinal couplings to methyl groups were 6.7 Hz, all geminal couplings were -15 Hz, and all other vicinal couplings were 7 Hz. The effect of relaxation during the mixing was not consideredTOCSY 生物大分子波谱学原理 吴季辉