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Hemes a and a3 environments of plant cytochrome c oxidase.

Abstract：

:The structures of hemes a and a3 of maize and wheat germ cytochrome c oxidase were investigated by resonance Raman spectroscopy. Comparison between the plant and mammalian cytochrome oxidases revealed that (i) the vinyl groups associated with hemes a and a3 vibrate at higher frequencies in the plant enzyme than in the mammalian enzyme, suggesting different degrees of interaction between the heme cores and their periphery; (ii) aside from the geometry of the vinyl group, the structure of heme a3 in plant cytochrome oxidase is essentially unchanged from that of its mammalian counterpart; (iii) the vibrational band associated with the formyl group of reduced heme a shows relatively weak enhancement in the Soret-excited resonance Raman spectra of maize and wheat germ cytochrome oxidase, suggesting that the formyl group of ferrous heme a in the plant enzymes is conjugated only slightly to the porphyrin ring; and (iv) for oxidized heme a, the formyl vibration is strongly enhanced, but its frequency indicates a weaker interaction with the protein milieu relative to the mammalian enzyme. These observations suggest that the local environment around the formyl position of the heme a chromophore differs in the plant and mammalian cytochrome oxidases. The implication of the latter feature in the mechanism of proton pumping by cytochrome oxidase is discussed.

journal_name

Biochemistry

journal_title

Biochemistry

authors

de Paula JC,Peiffer WE,Ingle RT,Centeno JA,Ferguson-Miller S,Babcock GT

doi

10.1021/bi00489a028

subject

Has Abstract

pub_date

1990-09-18 00:00:00

pages

8702-6

issue

37

eissn

0006-2960

issn

1520-4995

journal_volume

29

pub_type

杂志文章

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