This is the first lecture for Biochemistry BIOL2771 at Flinders University. It introduces enzymes, the terminology, and the enzyme-substrate complex. The lecturer was Associate Professor Kathy Schuller (KAS).
Week 1 Lecture 1
Introduction to Enzymes
All enzymes are proteins but not all biological catalysts are proteins, some are
made of RNA (called ribosomes)
Protein function is dependent on protein structure
Native structure vs. denatured structure
Some enzymes require inorganic elements (minerals) to perform their function
eg. Cu2+ (Cytochrome oxidase). Minerals are obtained from our diet.
Some enzymes require co-enzymes to perform their function eg. Flavin
adenine dinucleotide FAD (Riboflavin/Vitamin B2). Co-enzymes are organic
and they are synthesized from vitamins obtained from our diet.
Enzyme cofactors: Inorganic elements and coenzymes
Prosthetic group: A cofactor that is very tightly or even covalently bond to an
Enzymes are named according to the reaction they catalyse.
1. Oxidoreductases/Dehydrogenases: Transfer of electrons (hydride
ions or H atoms)
2. Transferases: Group transfer reactions
3. Hydrolases: Hydrolysis reactions (transfer of functional groups to
4. Lyases: Cleavage of C-C, C-O, C-N or other bonds by elimination,
leaving double bonds or rings, or addition of groups to double
5. Isomerases: Transfer of groups within molecules to yield isometric
6. Ligases: Formation of C-C, C-S, C-O, and C-N bonds by
condensation reactions coupled to cleavage of ATP
Enzymes have a pocket of amino acids called the active site eg.
Substrates interact with the active site of the amino acid thus a chemical
reaction occurs, releasing the product.
Allows enzymes to catalyse reactions under the mild conditions existing inside
our cells eg. Neutral pH at 37C
Increases the likelihood of the reactants (substrates) colliding in the correct
orientation for a reaction to occur
Binds the substrate transiently to form an enzyme-substrate complex
Be the first to comment on this document.