Elementary plant Biochemistry and Biotechnology (2+1)

Koshland’s induced-fit theory

• Koshland had advocated a theory to account for the specificity of enzymes.
  
• He postulated that the essential functional groups on the active site of the free enzyme are not in their optimal positions for promoting catalysis.
  
• When the substrate molecule is bound by the enzyme, the catalytic groups assume favourable geometrical position to form the transition state.
  
• The enzyme molecule is unstable in this active conformation and tends to revert to its free form in the absence of substrate.
  
• In the induced fit model, the substrate induces a conformational change in the enzyme which aligns the amino acid residues or other groups for substrate binding, catalysis or both.