C.1.1 enzymes and metabolism

Enzyme

Enzyme

a globular protein that increase the rate of biochemical reactions by lowering the activation energy threshold (e.g biological catalyst)

metabolism

a complex network of interdependent and interacting chemical reactions in occurring living organisms

enzymes are capable of?

enzymes are capable of reducing the energy needed for a chemical reaction to come together and react

enzymes are _____ and _____ ______ reactions

enzymes are specific and control metabolic reactions. Both anabolic and catabolic reactions.

substrate

a reactant in a biochemical reaction

the polar amino acids attract ____ and ____ of the enzyme

the polar amino acids attract substrate and active site of the enzyme

active site

a region on the surface of an enzyme that binds which binds substrates and which catalyze the reactions

once the substrate is locked into the active site?

the reaction is catalyzed. the products are released and the enzyme is used again.

The lock-and-key hypothesis

structurally: the 3D structure of the active site is specific to the substrate. substrates that don’t fit won’t react.

Chemically: substrates that are not chemically attracted to the active site won’t be able to react.

There are exceptions to the lock-and-key method, what is it?

Some enzymes can catalyze multiple reactions. As the substrate approaches the enzyme it induces a conformational change in the active site — it changes shape to the active site. This stresses the substrate and thus, lesser activation energy.

All molecules dissolved in water are in?

Random motion. Each molecule moving separately.

Most enzyme reactions occur when?

The substrates are dissolved in water

If not immobilized, the enzyme?

Can move too. However, enzymes tend to be larger than substrates and therefore move more slowly.

Collisions are the result of?

The random movements of both the substrate and the enzyme. The substrate may be in any angle to the active site when a reaction occurs.

Successful collisions are one in which?

The substrate and active site happen to be correctly aligned to allow binding to take place.

Collision theory:

• Molecules must collide in order to react

• Molecules must collide with the proper orientation such that the correct atoms can form a bond

• Molecules must possess a minimum amount of energy in order to collide with enough force to cause a reaction. The minimum amount of energy is called the activation energy.

The three-dimensional conformation of proteins is?

Stabilized by bonds or interactions between R groups of amino acids within the molecule. Most of these bonds are weak and can be disrupted or broken. This results in a conformational change in protein, which is called dénaturation.

Extremes of pH can cause dénaturation:

• charges on r groups are changed

• Breaking ionic bond within the protein or causing New Ionic bonds to form

Heat can cause dénaturation:

• Vibrations within the molecule breaks intermolecular bonds or attraction

A denatured protein normally does not return to its formal state:

The denature is permanent. Soluble proteins often become insoluble and forms a precipitate.

Enzymes are altered by environmental conditions:

• each enzyme has a highly specifically shaped active site which is complementary to the shape of its substrate: catalysts depend on this complementary