Lecture 2 - Reaction Mechanisms Flashcards
What are bisubstrate reactions?
Reactions that use two substrates and form two products.
What types of reactions can be bisubstrate reactions?
Transferases- functional group is transferred between the substrates.
Redox- reducing equivalents are transferred between substrates.
What is a sequential enzyme mechanism?
All substrates must combine with the enzyme before the reaction can occur and products can be released.
What is the difference between an ordered sequential mechanism and a random sequential mechanism?
Ordered- each substrate binds in a specific order and each product is released in a specific order.
Random- allows substrates to bind in any order and then products to be released in any order.
What are ping-pong kinetics?
One or more products are released before all of the substrates have bound to the enzyme.
How are the number of products/reactants specified in ping-pong kinetics?
As uni, bi, ter and quad.
- a reaction with one substrate and two products = uni bi
- a reaction with two substrates and two products = bi bi
What is denoted as A, B, C, D in ping pong mechanisms?
The substrates in the order they bind the enzyme.
What is denoted by E, F and G in ping pong mechanisms?
The stable forms of the enzyme - these can all be isolated and characterised. E denotes free enzyme, F is the first modified enzyme intermediate - with the transferred functional group attached.
What is denoted by P, Q, R, S in ping pong mechanisms?
The produces in the order they are released from the enzyme.
