Enzyme Models

(Cooper, 1997 p. ) 

 Two hypotheses for the way enzyme-substrate interact:
 
  1. Lock and key -Where the substrate is complementarity in shape, hydrophobic properties, ionic charge, and size to active site on enzyme (Fig. 2.24 in text).
  2. Induced fit -The active site becomes complementary only after the initial binding of enzyme to substrate (Fig. 2.24 in text).

 It turns out  that either one or the other of these two hypotheses works for every enzyme system known.

Induced fit seems to be most common. The substrate is placed under strain when enzyme binds, making the substrate more likely to lead to further reactions.

 Enzymes can bring 2 or more substrates together, distort their conformation andallow them to interact.

References:
Cooper, Geoffrey M. (1997) The Cell: A Molecular Approach; ASM Press, Washington, D.C. / Sinauer Associates, Inc., Sunderland, MA.