FBS Colloquia No.331Nano-Biophotonics Group

Vibrational Spectroscopy Study to Investigate Chlorophyll Biosynthesis

As a major pigment in photosynthesis, the biosynthetic process of chlorophyll can be investigated. The reduction of Protochlorophyllide to Chlorophyllide is the only light-dependent process which is a key regulatory step in the chlorophyll biosynthesis pathway. Finally, chlorophyll is synthesized after adding phytol tails. Photo-induced reduction happens when the trans-addition of hydrogen across the (C₁₇=C₁₈) double bond of protochlorophyllide is catalyzed by the light-driven enzyme Protochlorophyllide Oxido-Reductase (POR). Basically, the properties of light allow it to be absorbed, reflected, and transmitted. Understanding these phenomena has led to the development of spectroscopic research. Visible light is an electromagnetic wave with a wavelength range of 400-700 nm. Chlorophyll has photoreceptors that aid in biosynthesis and photochemical reactions, so it has optimal absorption in visible light, especially in the blue and red regions. To optimize this property, LEDs are used as artificial light sources for indoor agriculture because they have a narrow spectral distribution and can be applied in controlled environments. The LED light is absorbed by chlorophyll and the intensity is measured by the FTIR (600 – 4000 cm^-1). Vibrational spectroscopy can show chemical bond stretching in the chlorophyll structure. These molecular bonds are used to assign the corresponding compounds. Carbon-oxygen single bonds (C-O) correspond to carboxylic acids and carbon-oxygen double bonds (C=O) to aldehydes. Both are the main components that form chlorophylls.