Chapter 3: Enzymes

Inhibitor definition

A molecule that binds to an enzyme to prevent its activity

What are the 2 methods of inhibition?

Reversible and irreversible

What are the 3 mechanisms of inhibition?

• Competitive

• Uncompetitive

• Non-competitive

What’s reversible inhibition?

Where an enzyme isn’t permanently damage or changed

How does a molecule become active again after the inhibition has been reversed?

The inhibitor molecule will disjoin from the enzyme, allowing it to be reactive again

What are the two mechanisms that are reversible?

Competitive and non-competitive

What’s an irreversible inhibitor?

When a compound binds to the amino acid, forming a covenant bond

What are competitive inhibitors?

When the inhibitor has a similar shape to the substrate and will bind to the enzyme before the substrate, taking it’s place

What’s an uncompetitive inhibitor?

When the inhibitor binds to the enzyme-substrate complex, preventing a reaction from occurring

When’s an non-competitive inhibitor?

When the inhibitor binds to a non-active site of the enzyme, changing the active sites shape, preventing the substrate to bind.

Why does regulation of biochemical pathways occur?

• To prevent waste

• Prevent product buildup

• Prevent substrate depletion

What are the three components in allosteric regulation?

• Allosteric regulation

• Allosteric inhibition

• Allosteric activators

What’s allosteric regulation?

When an allosteric regulator binds to the active site or receptor on the enzyme to decrease enzyme activity

What’s allosteric inhibition?

When the inhibitor binds to the enzyme, changing its shape and stopping all enzyme activity

What’s allosteric activator?

The change in shape as a result of the activator binding to the enzyme, causing it to increase enzyme activity

What’s the feedback mechanisms in enzymes?

The end product of enzymes can act as inhibitors for the enzyme

What are co-factors?

An additional non-protein component that are necessary for enzymes activity and stability

Can co-enzymes be organic or non-organic

They can be both

What are co-enzymes?

Co-factors that act only when an enzyme is acting with a substrate

What are the co-enzymes used in photosynthesis and cellular respiration

• NADP

• NAD

• ATP

• CoA

• FAD

What’s NAD stand for?

Nicotinamide adenine dinucleotide

What’s NADP stand for?

Nicotinamide adenine dinucleotide phosphate

What’s FAD stand for?

Flavin adenine dinucleotide

What’s ATP stand for?

Adenosine triphosphate

What’s CoA stand for?

Co-enzyme A

What are the factors the affect enzyme activity?

• Temperature

• pH

• Enzyme concentration

• Substrate concentration

What does a higher temperature result in?

A higher kinetic energy of molecules, resulting in more collisions

What does a high temperature do for the substrates and enzymes?

The enzymes and substrates move faster, allowing for more reactions

What does each enzyme have?

An optimal temperature where an enzyme will work at max efficiency

What happens if the temperature goes above optimal temperature for enzymes?

It can denature

What does denaturing involve in enzymes?

The chemical bonds breaking down which changes the active site, rendering the enzyme inactive as it can’t bond with a substrate

What happens when the temperature is too low for enzymes?

The enzymes activity will stop all together

What happens when the temperature decreases?

The enzymes activity will decrease

What’s the optimum range?

The point where the max activity can occur

What’s the tolerance range?

The range in which an enzyme can still function, but not optimally

What happens outside the tolerance range to enzymes?

The enzyme can denature

What happens if the pH is too acidic or basic for the enzyme?

It can denature

What happens if the enzyme concentration stays the same but the substrate concentration increases?

The reaction rate will increase

What does the reaction rate increase when the enzyme concentration stays the same but the substrate concentration increases?

Because there’s more reactants available to undergo the reaction

What’s the saturation point?

When all the reaction rate can’t further increase

Why does the saturation rate happen?

Because all the enzymes in the cell are used up

Optimum temperature definition

Temperature at which the rate of reaction catalyzed by an enzyme is at its highest

What’s the effect on the enzymes when temperature decreases from optimum?

The rate of reaction decreases slowly which can inactive enzymes but not permanently

What’s the effect on the enzymes when temperature increase from optimum?

The rate of reaction decreases rapidly and if the temperature is too high it can lead to irreversible denaturing

Biochemical reactions definition

Reactions occurring in cells that lead to the formation of a product from the reactant

Biochemical pathways definition

A series of linked biochemical reactions

Cofactors definition

Non-protein molecules or ions that are essential for the normal functioning of enzymes

Coenzymes definition

An organic molecule that acts with an enzyme to alter the rate of reaction

How are cofactors involved in coenzymes?

Cofactors are loosely bound to their enzyme only when the enzyme is acting on a substrate

What are the 2 main roles of coenzymes?

• Energy transfer s

• Transfers of atoms or groups of atoms

What and when are the 2 inter-convertible forms of coenzymes?

• Loaded

• Unloaded

What happens when coenzymes are loaded?

They have a high energy forms that’s loaded with a group that can be transferred

What happens when coenzymes are unloaded?

They have a lower energy form that’s unloaded and nothing to be transferred

Loaded definition

A form of a coenzyme that acts as an electron doner

Unloaded definition

A form of a coenzyme that acts as an electron acceptor

What’s NAD unloaded and loaded forms

• Unloaded = NAD+

• Loaded= NADH