Olden K, Hempfling W P
J Bacteriol. 1973 Feb;113(2):914-21. doi: 10.1128/jb.113.2.914-921.1973.
Escherichia coli B was shown to contain a pigment with a single symmetrical absorption band at 503 nm, which cannot be attributed to a cytochrome. The absorption of tetrahydroporphyrin in vitro closely resembled that of P-503 in intact cells. The compounds which rendered P-503 colorless, such as cyanide, azide, hydrazine, thiocyanate, hydroxylamine, dithionite, sulfite, and methylcyanide, also rendered tetrahydroporphyrin colorless. The pigment was present when the cells were grown aerobically or anaerobically in glucose minimal medium, or aerobically in either lactate or succinate minimal medium, but the pigment was not found in cells grown in complex media or in minimal media supplemented with methionine. A model is presented to suggest the involvement of methionine in the conversion of coproporphyrinogen to protoporphyrin. A variety of evidence suggesting that the 503-nm chromophore is in kinetic equilibrium with flavoprotein is discussed. However, it is not a participant in main line respiration, as its rate of reduction upon exhaustion of oxygen was too slow, and the rate of respiration in resting-cell suspensions was independent of P-503 concentration.
已证明大肠杆菌B含有一种色素，其在503 nm处有一个单一的对称吸收带，该色素不能归因于细胞色素。体外四氢卟啉的吸收与完整细胞中P - 503的吸收非常相似。使P - 503无色的化合物，如氰化物、叠氮化物、肼、硫氰酸盐、羟胺、连二亚硫酸盐、亚硫酸盐和甲基氰化物，也能使四氢卟啉无色。当细胞在葡萄糖基本培养基中好氧或厌氧生长，或在乳酸盐或琥珀酸盐基本培养基中好氧生长时，该色素存在，但在复杂培养基中生长的细胞或添加了蛋氨酸的基本培养基中生长的细胞中未发现该色素。提出了一个模型，表明蛋氨酸参与了粪卟啉原向原卟啉的转化。讨论了各种证据，表明503 nm发色团与黄素蛋白处于动力学平衡。然而，它不是主线呼吸的参与者，因为在氧气耗尽时其还原速率太慢，且静息细胞悬液中的呼吸速率与P - 503浓度无关。
