In living organisms, a variety of biochemical reactions take place in physically confined spaces. Photosynthesis also occurs in the organelles, the chloroplasts of plants, and the smaller structures called ‘grana’ in chloroplasts absorb light. The DGIST team observed the reaction kinetics of biochemical reactions by creating microdroplets to look at the reaction of chlorophyll under the similar environment to the actual physical space of a plant.
The research team collided water droplets containing chlorophyll with water droplets containing hydrochloric acid at high speed to make micro-sized fused droplets. Then, they recorded kinetics of acid-induced chlorophyll demetallation by controlling the travelling distance of the fused microdroplets.
As a result, it was found that chlorophyll demetallation occurs at a time of several tens of microseconds, which is about a thousand times faster than that measured in bulk solution. This result is presumed to be due to the limitation of the physical space of microdroplets as well as the surface effect of droplets themselves.
Hong-Gil Nam said “When chlorophyll is oxidized, it loses its photosynthesis function. However, the demetallation reaction can protect the chlorophyll as it prevents the oxidation of chlorophyll.” He added “This study suggests that the demetallation reaction of chlorophyll can be a new mechanism which can protect photosynthetic organisms or control photosynthetic efficiency and that the reaction can be fast enough without any enzymatic action unlike conventional thinking.”
The team expects that the discovery of a new mechanism of photosynthesis would bring better understanding of the operation of photosynthesis and contribute to further studies to find elements and methods for more efficient photosynthesis.
Microdroplet fusion mass spectrometry: accelerated kinetics of acid-induced chlorophyll demetallation | Quarterly Reviews of Biophysics | Cambridge Core