Enzymes in motion - active site collisions and induced fit

what is specific to the substarte

the 3D structure and enzyme amino acid sequence of the active site

what does this shape ensure

active site binds to substrate molecule, holds and lower activation energy

what ensures an enzyme catalyses only specific reactions

high specificity and an induced shape change upon substrate binding

induced-fit model

model where enzyme and substarte have conformational change upon binding to each other

how does the induced-fit model differ from the lock-and-key model

induced fit involves flexible, complementary shape changes after binding, whereas lock-and-key assumes a rigid, pre-fit match; too restrcitive

where can enzymes be found

embedded and immobilised within a membrane, or are found in solutions (cytoplasm)

what is needed for a substarte and active site to come together

molecular movement, so they can collide

what happens when an enzyme is the ONLY one immobolised

the substrate has to do all the movement

what three aspects determine the formation of an enzyme-substrate complex

• molecular motion

• correct alignement and angle

• speed of movement

molecular motion

enzyme and substrates cause random collisions between molecules that occur in aqueous solution enabling continual motion

correct alignement and angle

determines the success of collsions between enzymes and substrates

speed of movement

affected by the molecules size, substartes are smaller than enzymes so movement is faster