mechanisms of enzyme action Flashcards
(28 cards)
define enzyme-product complex
enzyme molecule with product molecule in its active site. the two are joined temporarily by non-covalent forces
define enzyme-substrate complex
enzyme molecule with substrate molecules in its active site. the two are joined temporarily by non-covalent forces
what must happen in order for a reaction to occur
molecules need to collide in the right orientation
what happens when high temperatures and pressures are applied
the speed of the molecules will increase, therefore so will the number of successful collisions and the overall rate of reaction
what is activation
the energy supplied for a reaction to start
what happens if the amount of energy needed for a reaction is large and what helps overcome this
sometimes the amount of energy needed is large so it prevents the reaction from happening under normal conditions. enzymes help the molecules collide successfully and reduce the activation energy required
what binds to the active site
substrate
when is the protein inactive
when its unfolded - the primary structure is unfolded making it inactive
when does the protein become active
when the primary structure folds it become an active protein.
what is the folded shape of the protein
active site
what happens if two substrate molecules need to be joined together
the enzyme holds them together so they can bond more easily
what happens if the enzyme needs to catalyse a breakdown
when the substrate binds to the active site, the active site puts a strain on the bonds of the substrate so they can be broken easily
what does putting strains on the substrate prevent the need for
increasing temperature which you dont want to do inside the body otherwise other proteins will denature
how do enzymes lower activation energy
the active site changes shape so the bond easily breaks and there is no need to use more energy
what is the active site
indented area of the surface of a molecule. it is an area within the tertiary structure of the enzyme with a shape complementaty to the shape of a specific substrate molecule that binds to it
what is the lock and key hypothesis
that only a specific substrate will ‘fit’ the active site of an enzyme
describe the lock and key hypothesis
1) substrate molecules fit into the enzyme’s active site. temporary hydrogen bonds holding the two together forming an enzyme-substrate complex
2) the substrate molecules is broken down into smaller product molecules that leave the active site
3) the larger product molecule leaves the active site
how does an enzyme-substrate complex form
substrate molecules and enzymes molecules have kinetic energy and are constantly moving randomly. if a substrate molecule successfully collides with an enzyme molecules it forms a ESC as the substrate molecule fits into the complementary shaped active site on the enzyme molecule
what can happen to the substrate molecules
the substrate molecules are either broken down or built up into the product molecules and these form an ESC whilst still in the active site
what happens to the product
product molecules leave the active site
what can happen to the enzyme molecule
it can be reused
what can a small number of enzyme molecules do
convert a large number of substrate molecules into product molecules
how does the active site put a strain on the bonds of the substrate
the substrate is held in such a way by the enzyme that the right atom groups are close enough to react. the R groups within the active site of the enzyme will also interact with the substrate forming temporary bonds. these put strains on the bonds within the substrate which helps the reaction along
what is the induced fit hypothesis
the active site is not a fixed rigid structure but the presence of a substrate molecule in it induces a shape change giving a good fit
