A novel type haem group of cytochrome o from Escherichia coli.
The b-type haem groups of cytochrome o have generally been thought to be protohaems. However, we have recently shown that they are of a novel kind, for which we propose the name haem O. On the basis of its pyridine haemochrome spectrum, chromatographic behaviour and molecular mass of 839 Da, we suggest that haem O is a haem A-like molecule with the formyl group in position 8 of the latter replaced by methyl, but with retention of the 17-carbon hydroxyethyl-farnesyl side chain in position 2, characteristic of haem A. This structure has now been unambiguously verified by resonance Raman, 1H-NMR, and infrared spectroscopy, as well as by mass spectroscopy of molecular fragments, in collaboration with C. K. Chang, G. T. Babcock and their co-workers at Michigan State University. Properties of haem O are compared with haem A and protohaem, and possible contributions of haem O structure to the cytochrome o oxidase function are discussed.
Puustinen
A
A
Department of Medical Chemistry, University of Helsinki, Finland.
D002851:Chromatography, High Pressure Liquid; D003573:Cytochrome b Group; D003580:Cytochromes / Q000378:metabolism*; D004227:Dithionite; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins; D006418:Heme / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013055:Spectrophotometry, Infrared
D003573:Cytochrome b Group; D003580:Cytochromes; D029968:Escherichia coli Proteins; D004227:Dithionite; D006418:Heme; C017168:cytochrome bo, E coli