Open AccessNew insights into enzyme catalysis
Author(s) -
Scrutton Nigel S.,
Basran Jaswir,
Sutcliffe Michael J.
Publication year - 1999
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1999.00645.x
Subject(s) - quantum tunnelling , chemical physics , electron transfer , cleave , chemistry , kinetic isotope effect , quantum , enzyme catalysis , electron , bond cleavage , enzyme , physics , catalysis , quantum mechanics , photochemistry , biochemistry , deuterium
The wave‐particle duality of matter suggests that quantum tunnelling may have a prominent role in enzymatic H‐transfer. However, unlike for electron tunnelling, evidence for H‐tunnelling in enzyme molecules is extremely limited. The theoretical development, and verification by experiment, of a role for protein dynamics in driving enzymatic H‐tunnelling is presented. Dynamic theories of H‐tunnelling suggest that the kinetic isotope effect, during rupture of a C–H/C–D bond, for example, can assume values interpreted previously as indicating classical transfer. Vibrationally enhanced ground state tunnelling has been demonstrated for enzymes that cleave stable C–H bonds. This is an attractive mechanism as large activation energies make it energetically unfavourable for a classical, over‐the‐barrier mode of cleavage. Furthermore, it may be a general strategy used by enzymes for catalysing these ‘difficult’ transformations.