enzymes as catalysts Flashcards
what do enzymes do
- catalyse many chemical reactions which make up the process of metabolism
- speeds up the rate at which a reaction reaches equilibrium
- don’t affect the equilibrium position of a reaction
what are enzymes
- Mostly proteins. except some types of RNA that are catalysts
what conditions do enzymes work in
Work at body temp in aqueous solutions and near neutral pH.
how much can enzymes increase rate
by a factor up to 10^20
how are enzymes specific
each enzyme has a limited range of substrates, some can distinguish stereoisomers
how are enzymes potent
each enzyme molecule can convert many substrate molecules into product per second
how to enzymes lower activation energy
Enzymes specifically bind and stabilise the transition state
The transition state is the reaction intermediate species which has the greatest free energy
Enzymes reduce the activation energy by providing alternative reaction pathways
what does the catalytic activity of enzymes rely on
presence of cofactors and coenzymes
what are cofactors
metal ions. forms a metal co-ordination centre in the enzyme. The enzyme may be referred to as a “metalloprotein”.
what are coenzymes
organic molecules. mostly associate with the enzyme only transiently. They change charge or structure during the reaction but are regenerated.
what are tightly bound coenzymes called
prosthetic group
what is an enzyme without a cofactor called
apoenzyme
what is an enzyme with a cofactor called
holoenzyme
what do vitamins have to do with enzymes
- Most vitamins function as coenzymes, symptoms of vitamin deficiencies reflect the loss of specific enzyme activities. May be dietary or functional.
substrate binding to enzyme
- Substrate binds to an active site: a cleft or crevice, contains amino acids essential for catalytic activity, contains amino acids for highly specific interactions
