Publication: Control of C4a-hydroperoxyflavin protonation in the oxygenase component of p-hydroxyphenylacetate-3-hydroxylase
Issued Date
2014-07
Resource Type
Language
eng
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Mahidol University
Rights Holder(s)
American Chemical Society
Bibliographic Citation
Biochemistry. Vol.53, (2014), 4084-4086
Suggested Citation
Pirom Chenprakhon, ภิรมย์ เชนประโคน, Duangthip Trisrivirat, Kittisak Thotsaporn, Jeerus Sucharitakul, Pimchai Chaiyen Control of C4a-hydroperoxyflavin protonation in the oxygenase component of p-hydroxyphenylacetate-3-hydroxylase. Biochemistry. Vol.53, (2014), 4084-4086. doi:10.1021/bi500480n Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/3395
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Title
Control of C4a-hydroperoxyflavin protonation in the oxygenase component of p-hydroxyphenylacetate-3-hydroxylase
Abstract
The protonation status of the peroxide
moiety in C4a-(hydro)peroxyflavin of
p-hydroxyphenyla-
cetate-3-hydroxylase can be directly monitored using
transient kinetics. The p
K
a
for the wild-type (WT) enzyme
is 9.8
±
0.2, while the values for the H396N, H396V, and
H396A variants are 9.3
±
0.1, 7.3
±
0.2, and 7.1
±
0.2,
respectively. The hydroxylation e
ffi
ciency of these mutants
is lower than that of the WT enzyme. Solvent kinetic
isotope e
ff
ect studies indicate that proton transfer is not
the rate-limiting step in the formation of C4a-OOH. All
data suggest that His396 may act as an instantaneous
proton provider for the proton-coupled electron transfer
that occurs before the transition state of C4a-OOH
formation.