Schnackerz K D, Benesch R E, Benesch R, Kwong S, Ciurak M
Biochim Biophys Acta. 1984 Nov 9;790(3):226-9. doi: 10.1016/0167-4838(84)90026-8.
Deoxyhemoglobins substituted with pyridoxal 5'-phosphate or pyridoxal 5'-deoxymethylenephosphonate at the N-terminal amino groups of the alpha-chains were investigated by 31P-NMR spectroscopy. Titration curves of the 5'-side-chains show a substantial increase in acid strength in alpha-pyridoxylated deoxyhemoglobins when compared to the corresponding CO-liganded hemoglobins. These derivatives therefore contain a new oxygenation-linked acid group which opposes the normal Bohr effect. The loss in stabilization of the monoanion of the phosphate or phosphonate group derived from the three-dimensional structure can account for the lower pK of this ionization in deoxyhemoglobin as compared to CO-liganded hemoglobin. The reduction in the Bohr effect caused by modification of the alpha-chains with pyridoxal 5'-deoxymethyl-enephosphonate is quantitatively equal to the expected contribution of alpha-chain N-terminal amino groups.
通过³¹P-NMR光谱研究了在α链的N端氨基处被5'-磷酸吡哆醛或5'-脱氧亚甲基膦酸吡哆醛取代的脱氧血红蛋白。5'-侧链的滴定曲线表明，与相应的一氧化碳配体血红蛋白相比，α-吡哆醛化脱氧血红蛋白的酸强度显著增加。因此，这些衍生物含有一个新的与氧合相关的酸基团，它与正常的波尔效应相反。与一氧化碳配体血红蛋白相比，源自三维结构的磷酸或膦酸基团单阴离子稳定性的丧失可以解释脱氧血红蛋白中这种电离的较低pK值。用5'-脱氧亚甲基膦酸吡哆醛修饰α链所引起的波尔效应的降低在数量上等于α链N端氨基的预期贡献。
