ADD - Catalytic mechanisms + cofactors Flashcards
Semester 1 year 1
What bond do enzymes form with the substrate?
Covalent bonds to generate transient reactive intermediates
What are metalloenzymes?
-metals that are tightly bound
-usually transition metal ions
-usually permanently attached to enzyme
What is metal activated catalysis?
-metal is loosely associated
-typically alkali or alkaline earth metal ions
What is a coordination shell?
Describes the way in which any set of ligands around the metal have to be arranged
What are cofactors?
Certain enzymes require additional metal ions or small molecules to carry out their catalytic function
How often are cofactors used?
Normally used repeatedly + recycled in cells
What are coenzymes?
-the small organic molecules
-can be loosely or tightly bound
What are the names of tightly bound and loosely bound coenzymes?
-tightly bound - prosthetic groups
-loosely bound - cosubstrates
When on its own, what is the enzyme called?
Apoenzyme
When the cofactor is bound to the enzyme, what is the combination called?
Holoenzyme
What is AMP, what is it often a component of and what is it made up of?
-adenosine monophosphate
-often a component in cofactors
-made up of adenine, ribose + phosphate
What is a protein coenzyme?
-extra factor required is another small protein
-not catalytically active
-usually involved in transport
What is NAD?
-nicotinamide adenine dinucleotide
-major cofactor in cells
-composed of a nicotinamide ring, adenine ring, 2 ribose sugars + 2/3 phosphates
What is NAD used for?
Used in enzyme catalysed oxidations or reductions of substrate molecules
What does NAD convert between + what form is it commonly found in?
-converts between oxidised form (NAD+) + reduced form (NADH)
-found in 2nd form NADP (extra phosphate)
