Biology 190 Lab- Enzymes: Factors Affecting Their Rate and Activity

Metabolism

The cell carries out many chemical reactions. All the chemical reactions that occur in a cell.

Can enzymes be biocatalysts?

Yes, because they are made of proteins and function to increase the rate of chemical reactions to rates that are biologically useful rates

Enzyme catalyze

They accelerate reactions by lowering the activation energy needed for the reaction to occur

An enzyme must bind to what to from an enzyme-substrate complex?

It must bind to substrate molecule to form

How is the transition state formed?

By the complex distorts chemical bonds in which the substrates becomes more reactive and the metabolic reaction accelerates.

Energy of activation

The energy needed to from the transition state is lowered by the enzyme

What is an active site?

The attachment and the surrounding parts of the enzyme that stress the substrate's bonds

What is the function of the active site in an enzyme?

To constitute bonds that stress the substrate's bonds

What is it called when a reaction is complete?

Product which is formed and is relased from the enzyme

Enzyme function: Specificity

Most enzymes are very specific, performing one chemical reaction on one substrate.

Enzyme function: Substrate flexibility

A few enzymes can work on several substrates with similar chemical structures.

What factors can alter enzyme function?

Heat, pH, and salt concentration

How do changes in enzyme structure affect the rate of product formation?

Changes in enzyme structure slow the rate of product formation

What are the two types of inhibition seen with enzymes?

Competitive and non-competitive inhibition

What is competitive inhibition?

A type of inhibition where the inhibitor competes with the substrate for the active site of the enzyme

What is non-competitive inhibition?

A type of inhibition where the inhibitor binds to a site other than the active site, altering the enzyme's shape and function

Competitive inhibition

the inhibitor binds to the active site of the enzyme, the substrate and inhibitor are this competing for the same spot.

What type of inhibition can be overcome by increasing the substrate concentration?

Competitive inhibition

Why can competitive inhibition be overcome by increasing substrate concentration?

Because neither substrate nor inhibitor binds to the enzyme forever, and high levels of substrate favor the binding of substrate when the complex dissociates.

What is a non-competitive inhibitor?

It does not bind to the active site of an enzyme, but rather to another site on the enzyme, changing the shape of the active site and preventing substrate binding.

How does a non-competitive inhibitor affect enzyme activity?

It prevents the enzyme from working by altering the enzyme's active site, making it unable to bind substrate.

What is the function of tyrosinase?

It is a pathway that creates melanin, one of the pigments found in skin and hair.

What is the equivalent enzyme in plants to tyrosinase?

Catechol oxidase

In plants the creates what color pigment when exposed to air, and it also the reason why fruit trun brown after they have been sliced.

Brown

Procatechol

is a colorless liquid

The product from is hydroxyquinones

which means that it has a yellowish color. The apperance of the color indicate that a reaction has occurred between the enzyme.

What is denaturation?

Denaturation is when enzyme inhibitors cause the active site to undergo a conformational change, disrupting the enzyme's three-dimensional shape.

How do enzyme inhibitors affect substrate binding?

Enzyme inhibitors can affect substrate binding by causing the active site to undergo a conformational change, preventing substrate binding.

Metabolism

All the chemical reactions that occur in a cell

Enzymes

Biological catalyst composed of amino acids that function to increase the rate of chemical reactions

What is a substrate?

Substance on which an enzyme acts

What is the enzyme-substrate complex?

Complex formed when an enzyme binds to its substrate

What is the active site of an enzyme?

The part of the enzyme that binds to the substrate and facilitates the chemical reaction

What happens to the products once the reaction is complete in an enzyme-catalyzed reaction?

They are released from the enzyme

T/F: The enzyme is free to react with anothersubstrate

True

Enzymes Lower Activation Energy

energy needed tocomplete a chemical reaction

Hydroxyquinone + H2O

- The product formed will have a yellow color⮚ - More intense yellow = more hydroxyquinone

T/F: A temperature outside this range may denature (destroy) the enzyme and higher its activity

False: it lowers the activty

Optimal pH enzyme

2.4

Optimal pH for an intestinal enzyme

8.5

Buffers

Solution that will resist pH change

Differences Phenylthiourea and Tyrosinase

Phenylthiourea is a inhibitor of Tyrosinase. Tyrosine is a competitive substrate