Department of Biochemistry, Mahatma Phule Agricultural University, Rahuri, India 413 722.
Plant Physiol. 1992 Mar;98(3):984-7. doi: 10.1104/pp.98.3.984.
CO sensitivity of cytochrome a(3) in the leaves of a number of C(3) and C(4) plants was monitored by the nitrate reductase assay under differing CO to O(2) ratios. All the C(3) plants were relatively insensitive to CO and required a high CO to O(2) ratio of 40 to promote significant nitrate reductase activity. However, when treated with 2 millimolar 2,4-dinitrophenol, these leaves readily responded to CO even at low CO to O(2) ratios of 10 or less. On the other hand, the leaves of all C(4) plants tested, belonging to the three subgroups, were highly sensitive to CO, even at CO to O(2) ratios of 5 or less. In these leaves, the uncoupler was without any effect, probably because the mitochondria, either from mesophyll or bundle sheath cells or both, lacked tight respiratory control.
通过硝酸盐还原酶测定法,在不同的 CO 与 O₂ 比例下,监测了一些 C₃和 C₄植物叶片中细胞色素 a(3)对 CO 的敏感性。所有 C₃植物对 CO 的敏感性相对较低,需要高 CO 与 O₂ 比例为 40,以促进显著的硝酸盐还原酶活性。然而,当用 2 毫摩尔 2,4-二硝基苯酚处理时,这些叶片即使在 CO 与 O₂ 比例低至 10 或更低时,也能轻易对 CO 做出响应。另一方面,测试的所有 C₄植物叶片,属于三个亚组,对 CO 非常敏感,即使在 CO 与 O₂ 比例低至 5 或更低时也是如此。在这些叶片中,解偶联剂没有任何效果,可能是因为线粒体,无论是来自叶肉细胞还是束鞘细胞,或者两者都缺乏紧密的呼吸控制。