棕色脂肪组织线粒体内膜的有效质子传导率。对质子电化学势梯度的依赖性。
The effective proton conductance of the inner membrane of mitochondria from brown adipose tissue. Dependency on proton electrochemical potential gradient.
作者信息
Nicholls D G
出版信息
Eur J Biochem. 1977 Jul 15;77(2):349-56. doi: 10.1111/j.1432-1033.1977.tb11674.x.
The nucleotide-sensitive H+ (OH-) conducting pathway of mitochondria from the brown-adipose tissue of cold-adapted guinea-pigs passes an effective proton current which is directly proportional to the proton electrochemical gradient. At 23 degrees C and pH 7.0 this conductance is 16 nmol H+ - min-1 - mg-1 - mV-1. Addition of 0.2 mM GDP results in a conductance which is linear and low (0.7 nmol H+ - min-1 - mg-1 - mV-1) until deltamicronH+ exceeds 220 mV. At higher values of deltamicronH+, which can be attained by glycerol 3-phosphate oxidation but not palmitoyl-L-carnitine plus malate oxidation, the membrane conductance greatly increases, effectively limiting the maximal deltamicronH+ to 240 mV. High glycerol 3-phosphate concentrations which have the thermodynamic potential to exceed this value of deltamicronH+ instead create a greatly increased rate of controlled respiration. The generality and significance of this device to limit deltamicronH+, and its relation to the nucleotide-sensitive conductance, are discussed.
来自冷适应豚鼠褐色脂肪组织的线粒体的核苷酸敏感型H⁺（OH⁻）传导途径通过一种有效的质子电流，该电流与质子电化学梯度成正比。在23℃和pH 7.0时，这种电导率为16 nmol H⁺·min⁻¹·mg⁻¹·mV⁻¹。添加0.2 mM GDP会导致电导率呈线性且较低（0.7 nmol H⁺·min⁻¹·mg⁻¹·mV⁻¹），直到ΔμH⁺超过220 mV。在较高的ΔμH⁺值下（可通过甘油3 - 磷酸氧化达到，但棕榈酰 - L - 肉碱加苹果酸氧化无法达到），膜电导率会大幅增加，有效地将最大ΔμH⁺限制在240 mV。具有超过该ΔμH⁺值热力学潜力的高甘油3 - 磷酸浓度反而会使受控呼吸速率大幅增加。本文讨论了这种限制ΔμH⁺的机制的普遍性和意义，以及它与核苷酸敏感型电导率的关系。
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