TY - JOUR
T1 - Light-induced oxidation of cytochrome c
AU - Kotlyar, Alexander
AU - Borovok, Natalia
N1 - Funding Information:
Under conditionsw herew e haveb oththe free pyranine and the 1:1 complext he reactionr evealst wo well-dis-tinguishedp hases( seeFig. 4). At first we observea fast redoxe venth avinga time constantty picalo f intracomplex reaction( see Fig. 3). The rest of the reactionis significantly slower correspondinwgi th the collision controlled reactionb etweenP yrox and cytochromce. The fast-phase rate constant( 4.0___1 .0). 10 6 S-1 was independenot f cytochrome-cco ncentrationIn. contrastt,h e rate constant of the secondo ne (2.7 _ 0.2) • 105 s-1 increasews ith the concentratioonf cytochromec . This kinetic behavioris consistenwt ith combinationo f intracomplexa nd inter-moleculaer lectrontr ansfemr echanisms. Previouss tudiese mployedth ep hotoexcitatioonf photo-sensitivec ompoundtso reducec ytochromeasn d even cy-tochromeco mplexe\s[ 12-24\T]h. e oxidativep ulsem ethod, describedin this paper, is capableo f deliveringa mi-crosecondox idativep ulset o cytochromce. Being a strong oxidant( Em = 1 V) Pyrox may be employedfo r study of both the low and high potentiasl ectiono f the respiratory chain of mitochondriaan dbacteria. This researchis supportedb y the US Navy Office of Naval Research( Grant No. N00014-89-J1622a)n d the United States-IsraeBl inationalS cienceF oundation( 91-
PY - 1995/2/14
Y1 - 1995/2/14
N2 - Photooxidation of pyranine (8-hydroxypyrene-1,3,6-trisulfonate) by an intensive UV laser pulse (20-60 MW/cm2) leads to an instantaneous formation of the oxidized form of the dye. The redox reaction between the oxidized dye and ferrocytochrome c was followed by transient absorption spectroscopy looking either at re-reduction of oxidized pyranine or the oxidation of the cytochrome. At high ionic strength (100 mM Hepes and 20 mM KCI, pH 6.5), second-order kinetics of ferrocytochrome-c oxidation was observed with a rate constant of (3.2 ± 0.3) · 109 M-1s-1. At lower ionic strength a 1:1 complex was formed between the cytochrome and pyranine. The rate for intracomplex electron transfer was found to be (3.6 ± 0.2) · 106 s-1. This rapid photooxidation of cytochrome c makes it a useful tool for fast initiation of a synchronized electron flow within redox proteins.
AB - Photooxidation of pyranine (8-hydroxypyrene-1,3,6-trisulfonate) by an intensive UV laser pulse (20-60 MW/cm2) leads to an instantaneous formation of the oxidized form of the dye. The redox reaction between the oxidized dye and ferrocytochrome c was followed by transient absorption spectroscopy looking either at re-reduction of oxidized pyranine or the oxidation of the cytochrome. At high ionic strength (100 mM Hepes and 20 mM KCI, pH 6.5), second-order kinetics of ferrocytochrome-c oxidation was observed with a rate constant of (3.2 ± 0.3) · 109 M-1s-1. At lower ionic strength a 1:1 complex was formed between the cytochrome and pyranine. The rate for intracomplex electron transfer was found to be (3.6 ± 0.2) · 106 s-1. This rapid photooxidation of cytochrome c makes it a useful tool for fast initiation of a synchronized electron flow within redox proteins.
KW - Cytochrome c
KW - Electron transfer
KW - Photooxidation
KW - Pyranine
UR - http://www.scopus.com/inward/record.url?scp=0028847825&partnerID=8YFLogxK
U2 - 10.1016/0005-2728(94)00165-2
DO - 10.1016/0005-2728(94)00165-2
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AN - SCOPUS:0028847825
SN - 0005-2728
VL - 1228
SP - 87
EP - 90
JO - Biochimica et Biophysica Acta - Bioenergetics
JF - Biochimica et Biophysica Acta - Bioenergetics
IS - 1
ER -