Enzymes Flashcards
What type of proteins are enzymes ?
Globular
Why do reactions increase their rate due to temperature ?
More kinetic energy
More collision between substrate and active site
Why are enzymes important ?
They sustain life by ensuring that metabolic functions occur at faster rates, by lowering the activation energy level of biochemical processes.
Characteristics of an enzyme
Globular Tertiary Substrate specific Needed in Small quantities Could be recycled Does not change the direction of a reactio
What is the purpose of anabolic and catabolic reactions ?
To maintain balance - homeostasis
Exergonic reaction
Release energy
Endergonic
Absorb energy
Why is the active site so smaller than the enzyme ?
Protects the enzyme from free water molecules as active site contains r groups that may be hydrophilic.
Protects from external environment
Enzymes have varying degrees of specificity ?
Some have absolute specificity and bind to on but bind to no more than one.
The lock and key model
Only substrates with a complementary shape to the enzymes will bind with enzyme
How does heat denature enzymes?
Heat changes the shape of the enzyme which therefore is unable to bind to its specific substrate.
How is a substrate complementary to its enzyme?
Shape
Charge
Hydrophobic or hydrophilic nature
What amino acids line the active site ?
Substrate binding amino acids
Catalytic amino acids
Coenzyme
Helper molecules of enzymes which bind to the apoenzyme temporarily to activate an enzyme
Examples of coenzymes
NAD
FAD
Actyl
There are two types of amino acids in the active site , what are they!
Substrate binding amino acids
Catalytic amino acids
What does a substrate binding amino acid do
Bind to substrate
What does a catalytic amino acid do
Make or break bonds
There are two types of enzymes
Protein only enzyme
Apoenzyme
What is an apoenzyme
Has partially protein in its active site but it needs a coenzyme to bind it in its apoenzyme part.
Cofactors
Some enzymes need a cofactors or a particular ion for their activity.
Prosthetic group
Tightly bonded part of an enzyme .
Enzymes that involve in synthesis of reactions are said to be facilitating a
Anabolic reaction.
Anabolic reactions are
Endergonic reaction
Enzymes that involve in breaking down bonds are said to be facilitating a
Catabolic reaction
Catabolic reactions are
Exergonic
Feedback inhibition
This is when a product of an enzyme in a series of the biochemical process does not get consumed by another reaction so it accumulates and binds to the allosteric site of the first enzyme and therefore stops the entire process from progressing further
Effect of PH on active site
Changes the charges of the amino acid residues
What happens to enzymes when you increase the acidity?
H+ ions are increased
COOH- will become COOH
No COOH (carboxyll groups for enzymes to join with.
What happens when you increase the ph of enzymes’ environment
More OH- ions
Add to NH+3 to make NH2
No attraction between COOH- and NH3 .
Inactive precursors
Are enzymes which can attack the cell itself so are produced in the inactive form by the cells
Induced fit hypothesis
Shape of the active site varies slightly from that of the substrate and the two fit only after contact when the substrate induces a complementary shape
Reversible inhibitors
Competitive
Non competitive
Mixed
Uncompetitive
Irreversible inhibitors
Permanently modify the enzyme
Uses of inhibitors
Poison- used for defense (Artificial inhibitors are used for ;) Drugs Pesticides Herbicide Metabolic control
How can the effects of inhibitors be overcomed?
Increasing the substrate
Is the shape of the sure as substrate similar for a competitive or non competitive person ?
Competitive for similar
Non competitive have different shapes
Where does a non competitive inhibitor bind to in an enzyme ?
Allosteric site
Galactosemia
Galactose cannot be converted into glucose 1 phosphate which is an intermediate compound of galactose
Lactose intolerant
Enzyme lactase cannot be produced
PKU Phenylketonuria
Phenylaune hydroxylase enzyme is missing.
