The Enzymatic Activity of Phospholipase D (PLD) Illustrated

The cover image illustrates the enzymatic activity of phospholipase D (PLD), a soluble enzyme that hydrolyzes phospholipids, at the membrane interface. This image, composed 105-1-cover
of an Adobe Illustrator cartoon and a colorful image of a night sky, reflects the focus of our study on PLD enzymatic kinetics. These kinetics are complex as the lipid products of this reaction are charged and remain in the membrane, affecting the enzyme-membrane binding kinetics and hence, the overall enzymatic kinetics.  As illustrated, the accumulation of the charged lipids in the membrane can be probed locally by changes in ion conductance of gramicidin channels. In this study, we used the channel conductance measurements to derive the kinetics of PLD catalytic reaction and developed a model that describes these kinetics by considering the effect of product accumulation and substrate depletion in the membrane.

The artistic demonstrations are a powerful way of communication in science as the colorful and appealing images trigger our curiosity and draw us to the science story behind the image. Naturally, we always seek to find a creative and attractive image of our work to convey the message in an effective fashion. We hope that this image will attract the attention of Biophysical Journal readers towards the implications of heterogeneous catalysis on biomembrane surfaces for the kinetics of enzymatic activity – these processes can often not be described accurately with standard Michaelis Menten kinetics. More information about our recent work can be found at the following links:

Dr. Sheereen Majd
http://www.bioe.psu.edu/faculty/Majd.html

Dr. David Sept
http://septlab.engin.umich.edu

Dr. Michael Mayer
http://www.bme.umich.edu/labs/biomembrane/

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