Biology Reference
In-Depth Information
numbers vary enormously. A significant improvement in the
ability to use gel-based methods for protein quantitation and
detection was achieved with the introduction of two-dimensional
difference gel electrophoresis (2D DIGE), which enables co-
detection of several samples on the same 2DE gel, so avoiding
gel-to-gel variation ( 3-7 ).
Several chemical moieties have been found to be potential
regulators of cellular redox status. One of these, the free thiol
group (R-SH) of cysteine residues is a potent nucleophilic agent
and can undergo a number of redox-induced modifi cations under
physiological and pathological conditions. Modifi cations of R-SH
include the formation of protein disulfi des and mixed disulfi des
(e.g., with glutathione and free cysteine) and oxidation to the
sulfenic (R-SOH), sulfi nic (R-SO 2 H), and sulfonic (R-SO 3 H) acids
depending on the oxidative capacity of the oxidant ( 8 ). The R-SH
group can also be modifi ed by reactive nitrogen species to give the
S -nitrosylated form (R-SNO), while oxidized forms can be gluta-
thionylated for active secretion from cells or interconverted
between forms by various enzyme activities (see Fig. 1 ).
Numerous studies have combined 2DE with cysteine thiol
labeling to study redox-dependent protein changes. Maleimides,
iodoacetic acid, iodoacetamide, and other chemicals have been
modifi ed with labels (biotin, fl uorophores, radionuclides) to study
active secretion
from cells
altered
function?
gain of
function?
sulphonic acid
S-thiolation
R-SO 3 H
R-SSG
R-SS-R
GSSG
ROS
2
3
GSH
4
GSH
2
3
2
ROS/RNS
GSH/GSSG
ROS/RNS
GSH/GSSG
RNS
R-SO 2 H
R-SNO
R-SH
R-SOH
1
1
S-nitrosylation
sulphenic acid
sulphinic acid
ICy dye
1
peroxiredoxins, thioredoxin (thioredoxin reductase + NADPH)
2
3
4
glutathione peroxidase, glutathione S-transferases
protein disulphide isomerase/reductase, glutaredoxin, thioredoxin
glutathione reductase + NADPH
Fig. 1. Mechanisms of thiol-dependent cellular redox regulation. GSH reduced glutathione; GSSG oxidized glutathione; ROS
reactive oxygen species; RNS reactive nitrogen species.
Search WWH ::




Custom Search