Hydrogen-producing enzymes from green algae looked at for biotech potential

In Germany, Ruhr-Universität Bochum researchers are looking at how hydrogen-producing enzymes, or hydrogenases, could be a source of regenerative energy. A hydrogenase from the green alga Chlamydomonas reinhardtii , which has so far hardly been researched, has now been characterized more precisely by the RUB photobiotechnology working group.

Enzyme twin with biotechnological potential

Green algae have two almost identical hydrogen-producing enzymes. One has been researched for decades, the other received little attention – until recently.

Green algae have two almost identical hydrogenases. Although they differ in just one single amino acid, they have different properties, the Bochum team found.

The green algae hydrogenase CrHydA1 has been researched for decades. “The fact that there was another hydrogenase, CrHydA2, of almost identical construction in the same organism, was long dismissed as a curiosity,” says RUB researcher Dr. Vera Engelbrecht. “Because CrHydA2 had significantly lower hydrogen production rates compared to CrHydA1 and apparently did not fulfill any additional metabolic functions, this enzyme was not characterized in more detail for a long time. Now we have noticed remarkable differences. ”

Both enzymes can not only convert protons and electrons into hydrogen, but also catalyze the reverse reaction, i.e. gain electrons from the oxidation of hydrogen. However, both proteins prefer either one or the other reaction and thus have higher conversion rates for one reaction direction. While CrHydA1 shows a stronger tendency towards hydrogen production, CrHydA2 has higher rates of hydrogen oxidation. Responsible for these differences is a single amino acid near the active center, which works like a kind of molecular switch.

“Such a discovery can be useful for biotechnological application, because algae are becoming more and more attractive as living factories for the light-driven production of chemical substances,” explains Vera Engelbrecht. Energy, which is initially stored in the form of hydrogen, could be released again with the help of enzymes such as CrHydA2 and used for enzymatic bio-cascades – for example for the targeted production of cosmetics, medicines or food.