Wednesday, October 6, 2010

One Step At A Time

Consider again an uphill change from A to B with a steep barrier (tipping point): link

When faced with such a high barrier, it helps to break the uphill slog into steps. Catalysts (enzymes included) employ this strategy, breaking a reaction into one or more steps.*

Linus Pauling, that greatest of American chemists, introduced the profound notion that enzymes work by stabilizing tipping points (transition state energies in the parlance) and thereby speed things up:

Some of the acceleration occurs because requisite energy is just smoothly shaved off the peak, but sometimes a transient intermediate, labelled C above, appears. Thus we have a "stepwise" versus a "concerted" process.
*The 2010 Nobel prize was awarded to three inventors of a family of very similar catalysts.

1 comment:

  1. From the link: "One way in which enzymatic catalysis proceeds is by stabilizing the transition state through electrostatics."

    No doubt working via polarization.

    Told ya