enzyme structure and functions Flashcards
function of enzymes in catalyzing biological reactions
enzymes function to lower the activation energy of reactions
enzymes do not get used up
structure of an enzyme determines its function, so changing the structure can change the function of the enzyme
transferases
move a functional group from one molecule to another
A + BX to AX + B
ligase
join two large biomolecules (often the same type)
A + B to AB
oxioreductase
catalyze oxidation-reduction reactions that involve the transfer of electrons
oxidase = removes electrons from a molecule
reductase = gives electrons to a molecule
isomerase
interconversion of isomers, including both constitutional and stereoisomers
hydrolase
cleavage of bonds by the addition of water
lyase
cleavage of bonds without the addition of water or transfer of electrons
generate either a double bond or ring structure
acid/base catalysis
enzymes use acidic/basic properties to make reactions go faster by proton transfer
covalent catalysis
enzymes covalently bind to help with electron transfer
electrostatic catalysis
charged molecules or metal ions used to stabilize large positive or negative charges
proximity/orientation effects
enzymes make collisions between reacting molecules happen more often
transition state
has the highest energy point in a reaction
where you find the most instability
substrate-enzyme specificity
derives from structural interactions
enzymes can be specific enough to determine between stereoisomers
active site model
location on the enzyme where reaction with the substrate occurs
shape/characteristics of an active site are responsible for the specificity of the enzyme
induced-fit model
initial binding between the substrate and the enzyme is not perfect as the forces holding the two together are strong, but not at maximum strength
enzyme and substrate each change their shape to bind together tightly
binding between the reactant and enzyme is the strongest at the transition state
