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I am Francisco Laurindo,
Associate Professor at
the Heart Institute,
University of São Paulo,
School of Medicine, in Brazil.
Today, we'll talk about
protein disulfide isomerase
as a code for cell signaling.
I used to say it's not
just another thiol
protein. Oxidative stress is
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not actually a balance between
pro and anti oxidant mechanisms,
as it's usually
discussed. Nowadays,
we know that oxidative
stress is actually
the disequilibrium
of redox signaling.
Redox signaling occurs through
receptors such as cysteine
thiols or metals.
Today we'll focus on
cysteine thiols and
as you know, cysteine is
a very important amino acid to
promote the tertiary
structure of proteins.
We know nowadays that
cysteine have several
oxidative forms,
as we'll see in the next slide,
which we analyze
the landscape of
thiol modifications
in redox signaling,
we have oxidant reactions and in
the upper part, disulphide
exchange reactions.
As you can see, the thiol group,
the SH, are also
called sulfide group.
Normally it's ionized
to its thiolate,
an ion here as minus
and this confers
enhanced reactivity
towards oxidants
such as hydrogen
peroxide for example
and this promotes
several oxo forms
or oxidized forms
like sulfenic acid,
sulfenic acid, and
sulphonic acid.
Sulphonic and sulfenic
are reversible,
while sulphonic is
irreversible modification.
There are also several
other modifications like
sulfenamides, sulfenyl
amides and persulfide,
which confer a
significant amount
of versatility to thiol groups.
