chemical reactions and enzymes

Primary function of enzymes

They act as biological catalysts to speed up reactions.

Effect on activation energy

They lower the activation energy of chemical reactions.

Meaning of positive ΔG

The reaction will not occur without supplied energy.

Meaning of negative ΔG

It indicates a spontaneous chemical reaction.

Does ΔG indicate reaction rate?

No, ΔG does not indicate the rate.

Enzyme name suffix

They typically end in -ase.

Oxidoreductases function

They catalyze the transfer of electrons between molecules.

Transferases function

They catalyze the transfer of functional groups.

Hydrolases function

They add water to covalent bonds for breakdown.

Ligases function

They catalyze the joining of two molecules.

Active site role

Amino acids here determine substrate specificity.

Induced fit definition

A change in enzyme shape upon substrate binding.

Are all enzymes proteins?

No, some are RNA molecules called ribozymes.

Prosthetic groups

Non-amino acid molecules permanently bound to enzymes.

Inorganic cofactors

Inorganic ions permanently bound to enzymes.

Coenzymes

Non-protein carbon-containing molecules not permanently bound.

Allosteric regulation definition

An effector molecule binds to a non-active site.

Physical conditions affecting enzymes

Temperature and pH significantly affect enzyme function.

Oxidoreductases

Catalyze transfer electrons between molecules

Transferases

Catalyze the transfer of groups of atoms (functional groups) between molecules

Hydrolases

Add water to covalent bonds to break down molecules

Isomerases

Catalyze transfer of groups from one place to another within the same molecule

Ligases

Catalyze joining of two molecules together

Lyases

Catalyze non-hydrolytic breakage of bonds in molecules

Phosphatases

Catalyze the remove phosphate group from proteins

Phosphodiesterases

Catalyze hydrolysis of cGMP and cAMP

GTPase; ATPase

Catalyze hydrolysis of GTP / ATP

prosthetic groups

small molecules permanently attached to the enzyme, non-amino acids

inorganic cofactors

ions permanently bound to enzyme

coenzymes

Non-protein carbon containing molecule; not permanently bound