Breathing Exercises for Enzymes

A new model of proteins seeks to explain how enzymes extract energy form their vicinity and put it to use in regulating cell chemistry. Enzymes are huge protein molecules that play a crucial role in catalyzing chemical reactions among other molecules or atoms by lowering the energy barrier that would otherwise keep the reaction from happening. Enzymes can therefore be considered as energy-processing chemical-reaction-facilitating machines.

They are usually large, typically containing thousands of heavy (non-hydrogen) atoms, but of these only a few dozen atoms actually participate in the catalytic process. Addressing this important issue, a team of scientists at the Ecole Normale Superieure (Lyon, France) and the Ecole Polytechnique Federale de Lausanne (Switzerland) have concentrated on modeling the behavior of the stiff parts of the enzyme since they believe that some of the energy used in carrying out the catalytic task is stored not just as chemical energy (in the form of adenosine triphosphate, or ATP, the all-purpose “food” of cells) but also as mechanical energy in the form of a waggling or “breathing” motion in the stiffer parts of the enzyme.

Extending this research to proteins in general, Yves-Henri Sanejouand (yves-henri.sanejouand@ens-lyon.fr, 33-04-72-72-8870) says that he and his colleagues would like to scrutinize in more detail the nonlinear process by which some proteins catch and store thermal energy from their environment and also how chemical energy can be turned into mechanical energy, such as in muscle contraction. (Juanico et al., Physical Review Letters, upcoming article)