Chien J C, Dickinson L C
Proc Natl Acad Sci U S A. 1972 Oct;69(10):2783-7. doi: 10.1073/pnas.69.10.2783.
Single crystals of oxycobaltmyoglobin and deoxycobaltmyoglobin have been prepared and found to be isomorphous. The paramagnetic resonance spectra of deoxycobaltmyoglobin yield g(xx) = 2.33(0), g(yy) = 2.32(3), g(zz) = 2.02(8) with the z-axis parallel to the "heme" normal. The A(Co) and g tensors share the same principal axes with|A(Co) parallel| = 79 G and|A(Co)[unk]| = 6 G. A value of A(N) = 17.5 G was also obtained for the epsilon-N atom of the F8 histidine. There are two paramagnetic species in oxycobaltmyoglobin having apparently identical g-tensors (gxixi = 2.08(3), getaeta = 2.00(6), and gzetazeta = 1.98(9)) but different A(Co)-tensors. Furthermore, g values A(Co) do not share the same principal axes. The A(Co)-values for one of the species are (A(xx) = 16.7 G, A(yy) = 5.95 G, A(zz) = 9.3 G), they are all 40% larger for the other species. The two species are oriented 90 degrees to each other in the crystal. The results from electron paramagnetic resonance studies are consistent with a pi-bounded structure for (Co)MbO(2).
氧钴肌红蛋白和脱氧钴肌红蛋白的单晶已制备成功，并发现它们是同晶型的。脱氧钴肌红蛋白的顺磁共振谱给出g(xx)=2.33(0)，g(yy)=2.32(3)，g(zz)=2.02(8)，其中z轴平行于“血红素”法线。A(Co)和g张量具有相同的主轴，|A(Co)平行| = 79 G，|A(Co)垂直| = 6 G。对于F8组氨酸的ε-N原子，还得到A(N)=17.5 G的值。氧钴肌红蛋白中有两种顺磁物种，其g张量显然相同(gxixi = 2.08(3)，getaeta = 2.00(6)，gzetazeta = 1.98(9))，但A(Co)张量不同。此外，g值和A(Co)不具有相同的主轴。其中一种物种的A(Co)值为(A(xx)=16.7 G，A(yy)=5.95 G，A(zz)=9.3 G)，另一种物种的这些值都大40%。这两种物种在晶体中相互成90度取向。电子顺磁共振研究的结果与(Co)MbO₂的π键结构一致。
