Cho K H, Kim Y J
Department of Microbiology, College of Natural Sciences, Changwon National University, Korea.
Mol Cells. 2000 Aug 31;10(4):432-6.
Membranes of Pseudomonas nautica, grown aerobically on a complex medium, oxidized both NADH and deamino-NADH as substrates. The activity of membrane-bound NADH oxidase was activated by monovalent cations including Na+, Li+, and K+. The activation by Na+ was higher than that by Li+ and K+. The maximum activity of NADH oxidase was obtained at about pH 9.0 in the presence of 0.08 M NaCl. The NADH oxidase activity was completely inhibited by 60 microM 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO), while the NADH:quinone oxidoreductase activity was about 37% inhibited by 60 microM HQNO. The activities of NADH oxidase and NADH:quinone oxidoreductase were about 40% inhibited by 60 microM rotenone. The fluorescence quenching technique revealed that electron transfer from NADH to ubiquinone-1 (Q-1) or oxygen generated a membrane potential (deltapsi) which was larger and more stable in the presence of Na+ than in the absence of Na+. However, the All was highly sensitive to a protonophore, carbonyl-cyanide m-chlorophenylhydrazone (CCCP) even at alkaline pH.
在复合培养基上需氧生长的海生假单胞菌的细胞膜，能将NADH和脱氨基-NADH作为底物进行氧化。膜结合NADH氧化酶的活性被包括Na⁺、Li⁺和K⁺在内的单价阳离子激活。Na⁺的激活作用高于Li⁺和K⁺。在存在0.08 M NaCl的情况下，NADH氧化酶的最大活性在约pH 9.0时获得。NADH氧化酶活性被60 μM 2-庚基-4-羟基喹啉-N-氧化物（HQNO）完全抑制，而NADH：醌氧化还原酶活性被60 μM HQNO抑制约37%。NADH氧化酶和NADH：醌氧化还原酶的活性被60 μM鱼藤酮抑制约40%。荧光猝灭技术表明，从NADH到泛醌-1（Q-1）或氧气的电子传递产生了膜电位（Δψ），在存在Na⁺的情况下比不存在时更大且更稳定。然而，即使在碱性pH下，Δψ对质子载体羰基氰化物间氯苯腙（CCCP）也高度敏感。
