Biochemistry - Enzymes as Biological Catalysts Flashcards
What do enzymes do?
Catalyse chemical reactions by providing an alterative pathway and speeding up the rate at which equilibrium is achieved. Slide 3
What do enzymes not do?
Affect the position of equilibrium. Slide 3
What are enzymes key features?
Catalysts Mostly proteins Efficient - optimum environments Specific - limited range of substrates Potent - convert many substrates into products per second. Slide 4
What is the transition rate of enzyme action?
Where the reaction intermediate species has the greatest free energy. Slide 6
What do many enzymes depend on the presence of?
Cofactors or coenzymes. Slide 9
What are the two types of coenzymes/cofactors?
Metal ions - Inorganic (Cofactors)
Organic Molecules - Organic (Coenzymes). Slide 9
What do metal cofactors do?
Form a metal coordination centre in the enzyme which is called a “metalloprotein”.They are involved din redox reactions and stabilise transition states e.g. Zn, Fe, Cu. Slide 9
What do coenzymes do?
Associate with enzymes transiently and can change charge/structure but often regenerate. Derived from vitaments and involved din redox reactions e.g. NAD + FAD, also involved din group transfer processes e.g. CoA. Slide 9
What is a tightly bound coenzyme called?
Prosthetic group. Slide 9
What is an enzyme without a cofactor called?
Apoenzyme. Slide 9
What is an enzyme with a cofactor called?
Holoenzyme. Slide 9
What does NAD stand for?
Nicotinamide adenine dinucleotide. Slide 12
What does NAD do?
Can accept or donate electrons and is involved in the transport of protons. Slide 12
What does the active site of the enzyme contain to make it highly specific?
Contains amino acids essential for catalytic activity and also so there is highly specific interactions. Slide 13
What are isozymes?
They are isoforms of enzymes and can catalyse the same reaction but have different properties and structure. Slide 17
