{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,16]],"date-time":"2026-03-16T11:37:35Z","timestamp":1773661055644,"version":"3.50.1"},"reference-count":0,"publisher":"Portland Press Ltd.","issue":"3","content-domain":{"domain":["portlandpress.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[1993,2,1]]},"abstract":"<jats:p>Inner membranes were prepared from Escherichia coli strain RG 145, which is deficient in cytochrome bd, but overexpresses cytochrome bo [Au and Gennis (1987) J. Bacteriol. 169, 3237-3242]. The latter was purified 7-fold by extracting the membranes with octyl beta-D-glucopyranoside, followed by chromatography on DEAE-Sepharose, yielding 150 mg of protein\/150 g wet weight of cells. Optical e.p.r. and low-temperature m.c.d. (magnetic circular dichroism) spectroscopies were used to investigate the nature of the protein ligands to the two haems in cytochrome bo from E. coli. Low-spin ferric haem b, the origin of a rhombic e.p.r. spectrum with g = 2.98, 2.26 and 1.50, gives rise to a charge-transfer band in the near-i.r. m.c.d. spectrum at 1622 nm. It is therefore concluded that haem b is co-ordinated by two histidine residues. The low-temperature m.c.d. spectrum of dithionite-reduced cytochrome bo comprises bands due both to low-spin ferrous haem b and to high-spin ferrous haem o. The bands arising from haem o show a direct correspondence with those in the m.c.d. spectrum of five-co-ordinate histidine-ligated ferrous haems such as myoglobin, implying that the protein residue liganding haem o is also histidine. This assignment was confirmed by measuring the e.p.r. spectrum of the nitric oxide derivative of fully reduced cytochrome bo. This showed a rhombic spectrum with g = 2.098, 2.008 and 1.987, and nuclear hyperfine splitting consistent with the co-ordination of ferrous haem by NO and histidine. The hyperfine splittings observed were 1.95 +\/- 0.05 mT for the 14N of the NO ligand and 0.75 +\/- 0.05 mT for the 14N of the proximal histidine. The e.p.r. spectrum of some samples of oxidized cytochrome bo show, at temperatures below 15 K, broad signals at g = 7.6, 3.6 and 2.8, and other preparations in the presence of glycerol yield signals at g = 10.8, 3.2 and 2.6. These signals, which are abolished by the addition of cyanide, are assigned to the binuclear centre, cytochrome o-CuB, suggesting that the binuclear site may display heterogeneity. Carbon monoxide reacts with the reduced enzyme with a stoichiometry of 1:1, and the dissociation constant for this reaction was determined to be 1.7 x 10(-6)M. The second-order rate constants for this reaction were measured and shown to be similar to those determined for bovine cytochrome aa3 [Gibson and Greenwood (1963) Biochem. J. 86, 541-554].<\/jats:p>","DOI":"10.1042\/bj2890709","type":"journal-article","created":{"date-parts":[[2015,8,10]],"date-time":"2015-08-10T21:30:37Z","timestamp":1439242237000},"page":"709-718","update-policy":"https:\/\/doi.org\/10.1042\/crossmark_policy","source":"Crossref","is-referenced-by-count":46,"title":["Cytochrome <i>bo<\/i> from <i>Escherichia coli<\/i>: identification of haem ligands and reaction of the reduced enzyme with carbon monoxide"],"prefix":"10.1042","volume":"289","author":[{"given":"M R","family":"Cheesman","sequence":"first","affiliation":[{"name":"Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences, University of East Anglia, Norwich NR4 7T, U.K."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"N J","family":"Watmough","sequence":"additional","affiliation":[{"name":"Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences, University of East Anglia, Norwich NR4 7T, U.K."},{"name":"School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, U.K."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"C A","family":"Pires","sequence":"additional","affiliation":[{"name":"School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, U.K."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"R","family":"Turner","sequence":"additional","affiliation":[{"name":"School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, U.K."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"T","family":"Brittain","sequence":"additional","affiliation":[{"name":"Department of Biochemistry, University of Auckland, Auckland, New Zealand."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"R B","family":"Gennis","sequence":"additional","affiliation":[{"name":"Department of Biochemistry, University of Illinois, Urbana, IL 61801, U.S.A."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"C","family":"Greenwood","sequence":"additional","affiliation":[{"name":"School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, U.K."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"A J","family":"Thomson","sequence":"additional","affiliation":[{"name":"Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences, University of East Anglia, Norwich NR4 7T, U.K."}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"288","container-title":["Biochemical Journal"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/portlandpress.com\/biochemj\/article-pdf\/289\/3\/709\/609055\/bj2890709.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/portlandpress.com\/biochemj\/article-pdf\/289\/3\/709\/609055\/bj2890709.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2021,11,23]],"date-time":"2021-11-23T18:01:29Z","timestamp":1637690489000},"score":1,"resource":{"primary":{"URL":"https:\/\/portlandpress.com\/biochemj\/article\/289\/3\/709\/29800\/Cytochrome-bo-from-Escherichia-coli-identification"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1993,2,1]]},"references-count":0,"journal-issue":{"issue":"3","published-print":{"date-parts":[[1993,2,1]]}},"URL":"https:\/\/doi.org\/10.1042\/bj2890709","relation":{},"ISSN":["0264-6021","1470-8728"],"issn-type":[{"value":"0264-6021","type":"print"},{"value":"1470-8728","type":"electronic"}],"subject":[],"published":{"date-parts":[[1993,2,1]]}}}