Cross A B, Anthony C
Biochem J. 1980 Nov 15;192(2):429-39. doi: 10.1042/bj1920429.
The cytochrome complement of Methylophilus methylotrophus and its respiratory properties were determined during batch culture and in continuous culture under conditions of methanol-, nitrogen- and O(2)-limitation. About 35% of the cytochrome c produced by the bacteria was released into the growth medium, and of the remaining cytochrome c about half was membrane-bound and half was soluble. Two cytochromes c were always present on membranes (redox potentials 375mV and 310mV), and these probably correspond to the soluble cytochromes c described previously [Cross & Anthony (1980) Biochem. J.192, 421-427]. A third minor component of cytochrome c (midpoint potential 356mV) was only detected on membranes of methanol-limited bacteria. M. methylotrophus always contained two membrane-bound cytochromes b with alpha-band absorption maxima of about 556 and 563nm (measured at room temperature) and midpoint potentials of 110 and 60mV respectively. There appeared to be relatively more of the cytochrome b(563) in methanol-limited bacteria. A third b-type cytochrome with an alpha-band absorption maximum at 558 (at 77K) reacted with CO and had a high midpoint redox potential (260mV); it is thus a potential oxidase and hence is called cytochrome o. The roles of these cytochromes in electron transport were confirmed by investigating the patterns of respiratory inhibition. It is proposed that two cytochromes are physiological oxidases: cytochrome a+a(3), which is present only in methanol-limited conditions, and the cytochrome o, which is induced 10-fold in conditions of methanol excess. Schemes for electron transport from methanol and NAD(P)H to O(2) in M. methylotrophus under various limitations are proposed. Spectra and potentiometric titrations of cytochromes in whole cells and membranes of M. methylotrophus grown under various nutrient limitations have been deposited as Supplementary Publication SUP 50111 (10 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1978) 169, 5.
在分批培养以及甲醇、氮和氧气受限条件下的连续培养过程中，测定了嗜甲基甲基ophilus的细胞色素组成及其呼吸特性。该细菌产生的细胞色素c约35%释放到生长培养基中，剩余的细胞色素c约一半与膜结合，一半可溶。膜上始终存在两种细胞色素c（氧化还原电位分别为375mV和310mV），这可能与先前描述的可溶性细胞色素c相对应[克罗斯和安东尼（1980年），《生物化学杂志》192卷，421 - 427页]。细胞色素c的第三种次要成分（中点电位356mV）仅在甲醇受限细菌的膜上检测到。嗜甲基甲基ophilus始终含有两种与膜结合的细胞色素b，其α带吸收最大值分别约为556和563nm（在室温下测量），中点电位分别为110和60mV。在甲醇受限细菌中，细胞色素b(563)似乎相对较多。第三种b型细胞色素在77K时α带吸收最大值为558，能与CO反应且具有较高的中点氧化还原电位（260mV）；因此它是一种潜在的氧化酶，故而被称为细胞色素o。通过研究呼吸抑制模式证实了这些细胞色素在电子传递中的作用。有人提出两种细胞色素是生理氧化酶：仅在甲醇受限条件下存在的细胞色素a + a(3)，以及在甲醇过量条件下诱导量增加10倍的细胞色素o。提出了在各种受限条件下嗜甲基甲基ophilus中从甲醇和NAD(P)H到O(2)的电子传递方案。在各种营养受限条件下生长的嗜甲基甲基ophilus全细胞和膜中细胞色素的光谱和电位滴定数据已作为补充出版物SUP 50111（共10页）存放在英国西约克郡韦瑟比波士顿斯帕的大英图书馆出借部，邮编LS23 7BQ，可按《生物化学杂志》（1978年）169卷5页所示条件从该处获取副本。
