enzymes 1 Flashcards
co-factor apoenzymes co-enzyme holo-enzyme Prosthetic group
co-factor: the non-protein ( ion) component of the enzyme
apo-enzyme: the protein which contains the co-factor.
Holoenzyme: the apoezyme +co-factors.
co-enzyme: the complex molecule produced from a vitamin
Prosthetic group: the co-factor which is tightly bound to the enzyme
how are enzymes labelled?
usually based on function. 6 groups hydrolases ligases: form C-C, C-N,C-O,C-S bonds through ATP cleavage lyases: add, forms double bonds transferases oxidoreductases isomerases
what do enzymes do
1-lower the activation energy for a reaction by allowing the reaction to take place along an alternative pathway through reaction intermediates
2-allow the spontaneous reaction to take place faster
3-allow equilibrium to be reached quicker
what do enzymes NOT do
1- make a reaction spontaneous
2-alter the position of equilibria
Energy barrier
the energy requited to position all the atoms in correction orientation
transition state
the stage at which chemical bonds are formed/broken
how do enzymes work
decrease entropy: in solution molecules move around randomly. enzymes cause molecules to be orientated in the right direction so that ES form
desolution: replace h-bonds between hydrogen and substrate
induced-fit
michealis-merten equation
uses known substrate concentration to determine the Vmax (the fastest initial speed of reaction)
E+ s–> ES –> E+ P
first reaction is reversible
second reaction is not
so ES concentration is rate determining
at Vmax/2 –> substrate concentration= Km
at low Km, affinity is high so ES is stable and reaction proceeds faster
at high Km, affinity is low so ES is not stable and so reaction proceeds slowly.
Lineweaver-burk equation
uses the reciprocal values of M-M equation so 1/V and 1/S
it is used as it is often difficult to determine the Vmax as the rate of reaction will always increase slightly, does not plateau, so Km would be difficult to define.
