We report on the use of polymyxin (PM),
a cyclic c
ationic lipodec
apeptide,
as
an electrode modifier for studying protein film volt
ammetry (PFV) on Au
and single-w
alled c
arbon n
anotube (SWNT) electrodes. Pretre
ating the electrodes with PM
allows for the subsequent immobiliz
ation of
an
active submonol
ayer of [NiFe]-hydrogen
ase from
Allochromatium vinosum (
Av H
2ase). Probed by cyclic volt
ammetry (CV), the
adsorbed enzyme exhibits ch
ar
acteristic electroc
at
alytic beh
avior th
at is st
able for sever
al hours under continuous potenti
al cycling. An unexpected fe
ature of the immobiliz
ation procedure is th
at the presence of chloride ions is
a prerequisite for obt
aining electroc
at
alytic
activity. Atomic force microscopy (AFM) rel
ates the observed c
at
alytic
activity to enzym
atic
adsorption
at the PM/Au(111) surf
ace,
and
a combin
ation of concentr
ation-dependent CV
and AFM is used to investig
ate the inter
action between the enzyme
and the PM l
ayer.
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