scholarly journals Near-infrared magnetic and natural circular dichroism of cytochrome c oxidase

1980 ◽  
Vol 191 (2) ◽  
pp. 319-331 ◽  
Author(s):  
D G Eglinton ◽  
M K Johnson ◽  
A J Thomson ◽  
P E Gooding ◽  
C Greenwood
Keyword(s):  
Cytochrome C ◽  
Absorption Band ◽  
Cytochrome C Oxidase ◽  
High Spin ◽  
Room Temperature ◽  
Near Infrared ◽  
Sodium Dithionite ◽  
Cyanide Ion ◽  
Reduced State

A detailed study is presented of the room-temperature absorption, natural and magnetic circulation-dichroism (c.d. and m.c.d.) spectra of cytochrome c oxidase and a number of its derivatives in the wavelength range 700-1900 nm. The spectra of the reduced enzyme show a strong negative c.d. band peaking at 1100nm arising from low-spin ferrous haem a and a positive m.c.d. peak at 780nm assigned to high-spin ferrous haem a3. Addition of cyanide ion doubles the intensity of the low-spin ferrous haem c.d. band and abolishes reduced carbonmonoxy derivative the haem a32+-CO group shows no c.d. or m.c.d. bands at wavelengths longer than 700nm. A comparison of the m.c.d. spectra of the oxidized and cyanide-bound oxidized forms enables bands characteristic of the high-spin ferric form of haem a33+ to be identified between 700 and 1300nm. At wavelengths longer than 1300nm a broad positive m.c.d. spectrum, peaking at 1600nm, is observed. By comparison with the m.c.d. spectrum of an extracted haem a-bis-imidazole complex this m.c.d. peak is assigned to one low-spin ferric haem, namely haem a3+. On binding of cyanide to the oxidized form of the enzyme a new, weak, m.c.d. signal appears, which is assigned to the low-spin ferric haem a33+-CN species. A reductive titration, with sodium dithionite, of the cyanide-bound form of the enzyme leads to a partially reduced state in which low-spin haem a2+ is detected by means of an intense negative c.d. peak at 1100 nm and low-spin ferric haem a33+-CN gives a sharp positive m.c.d. peak at 1550nm. The c.d. and m.c.d. characteristics of the 830nm absorption band in oxidized cytochrome c oxidase are not typical of type 1 blue cupric centres.

scholarly journals Characterization of the partially reduced cyanide-inhibited derivative of cytochrome c oxidase by optical, electron-paramagnetic-resonance and magnetic-circular-dichroism spectroscopy

1981 ◽  
Vol 193 (3) ◽  
pp. 699-708 ◽  
Author(s):  
M K Johnson ◽  
D G Eglinton ◽  
P E Gooding ◽  
C Greenwood ◽  
A J Thomson
Keyword(s):  
Circular Dichroism ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Near Infrared ◽  
Magnetic Circular Dichroism ◽  
Circular Dichroism Spectroscopy ◽  
Paramagnetic Resonance ◽  
Magnetic Circular Dichroism Spectroscopy ◽  
Circular Dichroïsm ◽  
Reduced State

Optical. e.p.r. and near-infrared low-temperature m.c.d. (magnetic-circular-dichroism) spectroscopy were used to characterize the partially reduced cyanide-inhibited derivative of cytochrome c oxidase produced by anaerobic reductive titration with dithionite. The reductions of cytochrome a3+ and Cu2+a were followed by observation of the e.p.r. signals at g = 3.03, 2.21 and 1.5 and at g = 2.18, 2.03 and 1.99. As reduction proceeds new e.p.r. signals (g = 3.58 and 1.56) appear that quantify to give one haem per enzyme unit when a small excess of dithionite has been titrated in. The e.p.r. signal of the Cu2+a titrates in parallel with the disappearance of the band and 820nm in the optical absorption spectrum. The near-infrared m.c.d. spectrum shows the presence of the low-spin ferric haem, a3+, in the oxidized state of the enzyme, as a well-resolved positive peak at 1650nm. As reduction proceeds this band is replaced by one at 1550nm due to haem a3+(3)–CN in the partially reduced state. Hence as haem a3+(3)–CN becomes e.p.r.-detectable it also shows a near-infrared m.c.d. spectrum characteristic of a low-spin ferric haem. It is concluded that the partially reduced state of cyanide-inhibited cytochrome c oxidase contains a2+ . Cu+a . a3+(3)–CN . Cu+a3.

scholarly journals Image reconstruction of oxidized cerebral cytochrome C oxidase changes from broadband near-infrared spectroscopy data

2017 ◽  
Vol 4 (2) ◽  
pp. 021105 ◽  
Author(s):  
Sabrina Brigadoi ◽  
Phong Phan ◽  
David Highton ◽  
Samuel Powell ◽  
Robert J. Cooper ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Image Reconstruction ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Spectroscopy Data

scholarly journals The nature of haem a3 in the oxidized state of cytochrome c oxidase. Evidence from low-temperature magnetic-circular-dichroism spectroscopy in the near infrared region

1982 ◽  
Vol 207 (1) ◽  
pp. 167-170 ◽  
Author(s):  
A J Thomson ◽  
D G Englinton ◽  
B C Hill ◽  
C Greenwood
Keyword(s):  
Circular Dichroism ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Near Infrared ◽  
Magnetic Circular Dichroism ◽  
Infrared Region ◽  
Magnetic Circular Dichroism Spectroscopy ◽  
Near Infrared Region ◽  
Circular Dichroïsm ◽  
Inhibited Enzyme

The magnetic-circular-dichroism (m.c.d.) spectra of oxidized ‘resting’ bovine cytochrome c oxidase and the cyanide-inhibited form are reported at 5.15 T and at 4.2 K along with m.c.d. magnetization curves plotted at selected wavelengths. In both spectra there are features at 790nm and 1564nm due to Cua and haem a respectively, the e.p.r.-detectable components of the enzyme. There is a new peak at 1946nm only in the spectrum of the cyanide-inhibited enzyme. Arguments are advanced that assign this to low-spin ferric haem a3 bridged to Cua3, thereby forming a ferromagnetically coupled pair of metal ions.

Cat brain cytochrome-c oxidase redox changes induced by hypoxia after blood-fluorocarbon exchange transfusion

1995 ◽  
Vol 269 (2) ◽  
pp. H417-H424 ◽  
Author(s):  
M. Ferrari ◽  
M. A. Williams ◽  
D. A. Wilson ◽  
N. V. Thakor ◽  
R. J. Traystman ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Redox State ◽  
Near Infrared ◽  
Acute Hypoxia ◽  
Nir Spectroscopy ◽  
Severe Reduction ◽  
O2 Concentration ◽  
O2 Delivery ◽  
Sep Monitoring

We used rapid-scanning near-infrared (NIR) spectroscopy (730-960 nm) to study the effects of graded or acute hypoxia on cerebral cytochrome-c oxidase (cyt aa3) redox state in blood-perfluoro-carbon-exchanged cats with somatosensory evoked potential (SEP) monitoring. In graded hypoxia [10 min each at fractional inspiratory O2 concentration (FIO2) 0.9, 0.8, 0.7, 0.6, and 0.5], cyt aa3 reduction occurred at FIO2 0.6 when cerebral O2 delivery was < 3.5 ml.100 g-1.min-1. In acute hypoxia (FIO2 0.6 for 10 min), significant cyt aa3 reduction occurred from 5 to 10 min (cerebral O2 delivery 3.1 +/- 0.3 ml.100 g-1.min-1) and recovered with reoxygenation (FIO2 1.0). Cyt aa3 redox changes preceded or coincided with SEP alterations in both hypoxia protocols. These results demonstrate that cerebral cyt aa3 reduction occurs with severe reduction of cerebral O2 delivery, but no significant change in cerebral cyt aa3 redox state occurs with small reductions of cerebral O2 delivery. We conclude that substantial changes in cerebral cyt aa3 do not occur at physiological levels of O2 delivery and that current NIR clinical instruments would detect oxygen-dependent cerebral cyt aa3 redox changes only when O2 delivery is extremely compromised.

scholarly journals 1P179 X-ray structural analysis of the ligand-bound conformation of bovine cytochrome c oxidase in the reduced state(5. Heme protein,Poster Session,Abstract,Meeting Program of EABS & BSJ 2006)

2006 ◽  
Vol 46 (supplement2) ◽  
pp. S191
Author(s):  
Maki Tanuguchi ◽  
Kazumasa Muramoto ◽  
Kyoko Shinzawa-Itoh ◽  
Tomoko Maeda ◽  
Tomitake Tsukihara ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Poster Session ◽  
Heme Protein ◽  
X Ray ◽  
Meeting Program ◽  
Reduced State
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