Proton transfer from acidic or basic amino acid side chains (such as Histidine, Glutamate, or Aspartate) stabilizes unstable intermediates.
To isolate and characterize catalytic proteins, biochemists rely on specialized analytical workflows: Proton transfer from acidic or basic amino acid
By lowering the energy barrier required to transition reactants into the high-energy "transition state," a vastly larger fraction of substrate molecules possess enough kinetic energy to pass over the barrier at any given moment. It reflects the affinity of the enzyme for
. It reflects the affinity of the enzyme for its substrate; a lower Kmcap K sub m indicates higher affinity. Lineweaver-Burk Plot When a substrate binds
means high affinity, requiring less substrate to saturate the enzyme. The Lineweaver-Burk Plot Because determining Vmaxcap V sub m a x end-sub Kmcap K sub m
A transient covalent bond is formed between a nucleophilic amino acid side chain (like serine, cysteine, or lysine) and the substrate. This creates a highly reactive, short-lived enzyme-substrate intermediate. Metal Ion Catalysis
Modern enzymology favors Daniel Koshland’s . This theory posits that the enzyme is flexible. When a substrate binds, it induces a conformational change in the enzyme structure, wrapping the active site tightly around the substrate and forcing it into a highly reactive transition state. Coenzymes, Cofactors, and Prosthetic Groups Many enzymes require non-protein components to function: Cofactors: Inorganic ions (e.g., Mg2+cap M g raised to the 2 plus power Fe2+cap F e raised to the 2 plus power Zn2+cap Z n raised to the 2 plus power ) that stabilize charge distributions during catalysis.