Team:Utah State/Results/Chlorophylasse

Chlorophyll is a photopigment found in the chloroplast of green plants. Chlorophyll absorbs light strongly in the blue and red regions of the visible spectrum. It absorbs very poorly in the green region, and that light is reflected, hence, making plants green. Chlorophyll is an excellent photoreceptor because it contains networks of alternating single and double bonds. Because, the electrons are not held tightly to a particular atom and can resonate, they can be readily excited by light. There are two varieties of chlorophyll molecules, chlorophyll a and chlorophyll b. They have small differences in absorbance spectrums allowing the plant to absorb and utilize more of the sun’s energy. The power of chlorophyll is its ability, when excited, to transfer an electron to an acceptor creating a separation of charge and chemical potential. Thus, light energy is converted into chemical energy (Tymoczko et. al., 2010).

Chlorophyll is naturally degraded during normal turnover of the pigment, when leaves change colors during fall, when fruit ripens, and during triggered cell death due to extreme temperature or water shortage. The first step in the breakdown of chlorophyll is catalyzed by the enzyme chlorophyllase. Chlorophyll is broken down into chlorophyllide and phytol. Chlorophyll is a dark green and hydrophobic molecule while chlorophyllide is a lighter green and hydrophilic (Arkus et. al, 2007). The chlorophyllase enzyme obtained for our project was cloned from a species of wheat, Triticum aestivum. Chlorophyllide is further broken down by a series of enzyme-catalyzed reactions into colorless final products (Eckhardt et. al, 2004).

Green grass stains are actually chlorophyll stains. When a grass stain occurs the friction caused from sliding the plant over the material breaks cell membranes. This releases chlorophyll and other proteins into the fabric. Because chlorophyll is similar in chemical structure to natural fibers like cotton and wool it binds to the fabric making it difficult to remove with regular detergents (Rodriguez, 2003). Our project aims to synthetically produce the enzyme chlorophyllase that will begin the degradation of chlorophyll. As chlorophyll is degraded into chlorophyllide, it will become more water soluble. The green, water soluble, stain will then be easier to remove with normal washings.

References

Tymoczko, J., Ber. J., Stryer, L. (2010) Biochemistry a short course. Ahr, K. (Ed.). New York, NY: W.H. Freeman and Company

Rodriguez, M (2003). Difficulty of grass stain removal. Message posted to http://www.newton.dep.anl.gov/ askasci/gen01/gen01433.htm

Arkus, K. A., Jez, J. M. (2008). An integrated protein chemistry laboratory. Biochemistry and Molecular Biology Education, 36(2), 125-128.

Eckhardt, U., Grimm, B., & Hörtensteiner, S. (2004). Recent advances in chlorophyll biosynthesis and breakdown in higher plants. Plant molecular biology, 56(1), 1-14.