Two Ways in Which a Substrate Binds on The Active Site of an Enzyme

My roommate and I are both right because there are two ways in which a substrate binds on the active site of an enzyme. The model that I am talking about is called the lock and key model theory that states that an enzyme with an active site has a specific shape that can only fit a substrate with that specific shape. The substrate will then act like a key and the active site as the lock, so that when the substrate attaches to it becomes activated and allows for reactions to occur that ultimately lead to the formation of products. There is another model called the induced fit theory that makes my roommate correct as well because there is more than one way a substrate can bind. In the induced fit model theory, it states that when the correct substrate binds to the active site of an enzyme, it will respond to the binding of the substrate causing it to change the shape and conformation of it.

if K=1 then ?G° = 0 and is in equilibrium

if K>1 then ?G°

if K 0 and is endergonic

How is the overall free energy of a reaction useful for understanding enzyme function?

The standard free energy of a reaction will let you know whether a reaction will be spontaneous. This is important because with this we are able to tell whether the reaction is exergonic or endergonic. If the delta G is negative the reaction will be spontaneous in other words exergonic. If the delta G is positive then the reaction will require you to put in energy and in other words endergonic. This is vital because if a reaction is endergonic it needs a little help of enzymes that will help move the reaction forward. The enzyme will help by bringing down the activation energy of the reaction down and will help create the transition state, which is through the binding of the enzyme through the substrate.

Transition-state analogs are chemical compounds that resemble the structure of a transition state of a catalyzed reaction and are potent inhibitors of enzymes. These transition-state analogs are considered inhibitors because they will bind to the enzyme a lot tighter than a substrate will. The transition-state analogs mimic the transition state of a reaction but they do not allow the enzyme to be activated treating it as an inhibitor to the enzyme.

The way in which enzymes help to facilitate the formation of the transition state is that they serve as catalysts that help by decreasing the free energy of activation of these chemical reactions. Enzymes speed up the reactions and help the formation of the transition-state by creating a pathway that allows the transition state to have its free energy lowered and allows products to be formed faster than an uncatalyzed reaction would. It does this by combining the substrate and the enzyme which then creates the transition-state pathway and its energy is lower than it would be without the enzymes. Since the activation energy is now lowered, more of these molecules are able to reach the transition-state and create more products in a shorter amount of time. This is also known as catalysis, which also stabilizes the transition state.

In the concerted model the allosteric proteins are multi-subunit proteins with effector and substrate binding sites on each subunit, binding of a substrate or effector molecule stabilizes the R form of a subunit, stabilizing the R form for all the subunits, this is an "all-or-none" Model where all the protein subunits are in the R state or T state. In the sequential model binding of the effector or substrate molecule stabilizes one subunit in the R state, the bound subunit influences the stability of an adjacent subunit that will subsequently be stabilized in the R state on binding of a substrate or effector model and this is not an "all or none" model since there can be forms of protein with 1, 2, or more subunits.

The Michaelis-Menten equation is V0 = Vmax(S/(S + KM))

V0 is the reaction velocity

Vmax is the Maximum velocity. It is the maximum rate of enzyme catalysis when it is saturated with substrate

S is the Substrate concentration

KM Michaelis-menten constant it is the substrate concentration at ½ Vmax

In competitive inhibition, it works by having the natural substrate compete the higher the concentration of the inhibitor, the more likely the probability that the enzyme will bind to it rather than to the substrate. In noncompetitive or mixed inhibition can bind an enzyme that’s already bound to a substrate. These inhibitors work by inhibiting the enzyme activity directly. In uncompetitive inhibition, they work by binding at a different site to the substrate. They bind to the ES complex and work by inhibiting the enzyme activity.