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0:00
Welcome, everybody. My
name is Michael Schrader.
I'm a professor of
cell biology in
the Department of Biosciences
at the University of Exeter.
In my short talk, I would
like to introduce
peroxisomes to you.
0:18
What are peroxisomes?
Peroxisomes are
membrane-bound organelles
found in almost all
eukaryotic cells.
They were first
characterised and named by
Nobel Laureate Christen
de Duve in the 1960s,
and he used gradient
centrifugation to isolate
the organelles and
revealed that they contain
several oxidases which
use oxygen to convert
a specific substrate
into a product,
thereby generating
hydrogen peroxide.
The hydrogen peroxide is
decomposed by catalase,
one of the most prominent
peroxisomal marker enzymes.
Based on these functions,
de Duve named the
organelle peroxisome.
We now know that
peroxisomes are also
involved in other
metabolic processes,
in particular in lipid metabolism
and detoxification reactions.
Peroxisomes are highly dynamic
and adaptable organelles.
They can change morphology,
number, and protein content
upon environmental changes,
and defects in the organelle
can cause serious
human disorders.
1:37
How do peroxisomes look like?
What's the structure
of peroxisomes?
They are usually
small, spherical,
or oval-shaped organelles,
but not always.
They can also be tubular
or elongated with
membrane protrusions.
They are surrounded by a
single lipid bilayer membrane
and contain a fine granular
matrix in the lumen.
You can see this here in the
electron microscopy image.
The lumen contains
the matrix enzymes,
the enzymes of the peroxisomes,
for example, catalase.
You can see that in
the immuno-electron
microscopy catalase
labeled by gold particles
is uniformly distributed
in the matrix.
However, peroxisomes
can also contain
crystalline inclusions
or so-called cores
of oxidative enzymes,
and you can see in the
immuno-electron microscopy
that urate oxidase forms
such a crystalline core.
Peroxisomes do not contain DNA.
They rely solely on
nuclear-encoded proteins.
Peroxisomes are
ubiquitous organelles.
