hu wissen 3 (pdf) - Humboldt-Universität zu Berlin

Die Mikrobiologen der HU sind
bereits jetzt in der Lage, mit
Hilfe von Hydrogenasen aus
Licht und Wasser umweltfreundlichen
Wasserstoff zu gewinnen
Microbiologists from the Department
of Biology at HU are already
in a position to produce environmentally-friendly
hydrogen from
water and light
He has already managed to mimick part of the enzyme active
centre using molecules and to simulate its activity. Limberg also
tests the catalytic potential of the model compounds developed by
the chemists.
Another type of enzymes that Limberg is partially recreating
in collaboration with HU biologists are hydrogenases, which can
produce molecular hydrogen. Microbiologists Oliver Lenz and
Bärbel Friedrich from the Department of Biology at HU are already
in a position to produce environmentally-friendly hydrogen
from water and light using hydrogenases and the photosynthetic
apparatus of a cyanobacterium. »The problem is that hydrogenases’
metal centres not only react with hydrogen, but also with oxygen,
which deactivates or destroys the enzymes,« says Lenz. This
negative attribute limits the biotechnical applications of conventional
hydrogenases. However, there are a small number of hydrogenases
that are barely affected by oxygen. Why some hydrogenases
are oxygen resistant or tolerant and some are not is
something that Lenz was recently able to work out in cooperation
with partners at UniCat, the University of Oxford and the Max
Planck Institute for Dynamics of Complex Technical Systems. »We
were able to show that oxygen-tolerant hydrogenases have a
highly specialised electron transport chain, which can transfer
electrons to the active centre where they convert harmful oxygen
into harmless water.« Furthermore, the HU microbiologists recently
teamed up with partners at the Charité to use X-ray crystallography
to examine the 3D structure of an oxygen-tolerant hydrogenase.
»The enzyme has an iron-sulphur centre − something we
have never seen before − which acts as an electronic switch that
plays a key role in ›detoxifying‹ the otherwise harmful oxygen.« As
well as focusing on hydrogenases, HU chemists are also performing
modelling studies on oxygenases. They are able to use oxygen
to oxidise hydrocarbons into more valuable substances. These important
reactions are also the key area of another Cluster research
group, headed by theoretical chemist Professor Joachim Sauer.
The team is searching for suitable heterogeneous catalysts – purely
inorganic solids which facilitate reactions on their surface.
138