Lepeshkevich Sergei V, Karpiuk Jerzy, Sazanovich Igor V, Dzhagarov Boris M
Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70 F. Skaryna Ave., Minsk 220072, Belarus.
Biochemistry. 2004 Feb 17;43(6):1675-84. doi: 10.1021/bi034928q.
Laser flash photolysis technique is used to study human hemoglobin (HbA) oxygenation. Monomolecular geminate oxygenation of triliganded R-state HbA molecules is described by a function of three exponentials. Geminate oxygenation of the alpha-subunit within R-state HbA is characterized by two components with time constants of 0.14 and 1 ns, while geminate oxygenation of the beta-subunit within HbA is characterized by two components with time constants of 1 and approximately 30 ns. Bimolecular oxygenation of triliganded R-state HbA molecules is described by a biexponential law. Two observed rate constants are assigned to oxygenation of the alpha- and beta-subunit within HbA. The bimolecular association rate constants for O(2) rebinding with the alpha- and beta-subunit within triliganded R-state HbA are k(alpha) = 18.8 +/- 1.3 (microM x s)(-1) and k(beta) = 52 +/- 4 (microM x s)(-1), respectively. The apparent quantum yields of photodissociation of the beta- and alpha-subunit within completely oxygenated R-state HbA differ from each other by a factor of 3.6 and are equal to 0.041 +/- 0.004 and 0.0114 +/- 0.0012, respectively. The apparent quantum yield of photodissociation of completely oxygenated R-state HbA is equal to 0.026 +/- 0.003.
激光闪光光解技术用于研究人血红蛋白（HbA）的氧合作用。三配位R态HbA分子的单分子双生氧合作用由一个包含三个指数的函数描述。R态HbA内α亚基的双生氧合作用由两个时间常数分别为0.14和1纳秒的成分表征，而HbA内β亚基的双生氧合作用由两个时间常数分别为1和约30纳秒的成分表征。三配位R态HbA分子的双分子氧合作用由双指数定律描述。两个观察到的速率常数分别对应于HbA内α亚基和β亚基的氧合作用。三配位R态HbA内O(2)与α亚基和β亚基重新结合的双分子缔合速率常数分别为k(α) = 18.8 +/- 1.3（微摩尔×秒）(-1)和k(β) = 52 +/- 4（微摩尔×秒）(-1)。完全氧合的R态HbA内β亚基和α亚基的光解离表观量子产率相差3.6倍，分别为0.041 +/- 0.004和0.0114 +/- 0.0012。完全氧合的R态HbA的光解离表观量子产率为0.026 +/- 0.003。
