Haemoprotein b-590 (Escherichia coli); Redesignation of a Bacterial ‘Cytochrome a1'

SUMMARY: A ‘soluble’ fraction from anaerobically grown Escherichia coli contains a haemoprotein with spectral properties, notably an α-band in the reduced form at 585 to 595 nm, similar to cytochrome a 1. Haem extraction of either the soluble preparation or whole cells yields haem b, but not haem a. In view of this, and the spectral similarities of the a 1-like component to well-known high-spin haem b proteins, we propose that the name ‘haemoprotein b-590’ be used to describe this substance and that consideration be given to the applicability of the name to certain other cytochrome a 1-like pigments in bacteria.