Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Query: EC:1.12.7.2 (
hydrogenase
)
3,522
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Complicated pH-properties of the tetraheme cytochrome
c
3
(cyt
c
3
) from
Desulfovibrio vulgaris
Miyazaki F (
Dv
MF) were examined by the pH titrations of
1
H-
15
N HSQC spectra in the ferric and ferrous states. The redox-linked p
K
a
shift for the propionate group at
C13
of heme 1 was observed as the changes of the NH signals around it. This p
K
a
shift is consistent with the redox-linked conformational alteration responsible for the cooperative reduction between hemes 1 and 2. On the other hand, large chemical shift changes caused by the protonation/deprotonation of Glu41 and/or Asp42, and His67 were redox-independent. Nevertheless, these charged residues affect the redox properties of the four hemes. Furthermore, one of interesting charged residues, Glu41, was studied by site-directed mutagenesis. E41K mutation increased the microscopic redox potentials of heme 1 by 46 and 34 mV, and heme 2 by 35 and 30 mV at the first and last reduction steps, respectively. Although global folding in the crystal structure of E41K cyt
c
3
is similar to that of wild type, local change was observed in
1
H NMR spectrum. Glu41 is important to keep the stable conformation in the region between hemes 1 and 2, controlling the redox properties of
Dv
MF cyt
c
3
. In contrast, the kinetic parameters for electron transfer from
Dv
MF [NiFe]
hydrogenase
were not influenced by E41K mutation. This suggests that the region between hemes 1 and 2 is not involved in the interaction with [NiFe]
hydrogenase
, and it supports the idea that heme 4 is the exclusive entrance gate to accept the electron in the initial reduction stage.
...
PMID:Roles of charged residues in pH-dependent redox properties of cytochrome
c
3
from
Desulfovibrio vulgaris
Miyazaki F. 2785 59
