co-enzymes Flashcards
what are co-factors and co-enzymes
They are small molecules that many enzymes depends on for catalysis of reaction
The enzyme without its cofactor is called
apoenzyme
When it has its cofactor its called
holoenzyme
what are co-factors
Co-factors are simple inorganic ions that promote enzyme function e.g. Zn Cu,Fe.
Make it fold and create an active site
Enhance the charge in the active site to improve substrate binding
what co-factor does amylase require
amylase requires chloride ions
what are co-enzymes
Small organic molecules attach to activate the enzyme and detach when reaction completed to deactivate the enzyme..
Coenzymes act as transporters of chemical groups from one reactant to another.
give examples of co-enzymes
Most often these are vitamins e.g. Niacin, riboflavin
what are isozymes?
Isozymes (also known as isoenzymes) are enzymes that differ in amino acid sequence but catalyse the same chemical reaction.
what are the differences in the isozymes?
These enzymes usually display different kinetic parameters (e.g. different Km values), or different regulatory properties.
what permits the fine-tuning of metabolism to meet the particular needs of a given tissue or developmental stage
isozymes
Hurler syndrome is an enzyme deficiency disease.what is it?
- abnormal bone structure and developmental delay
- accumulation of glycosaminoglycan Heparan sulfate (long chain sugar molecule soften found in mucus & fluid around the joints) .
An enzyme responsible for the degradation of mucopolysaccharides in lysosomes
Enzyme replacement therapy
& bone marrow replacement
Niemann-Pick disease
Lack acid sphingomyelinase (ASM)
.This lysosomal enzyme is required to metabolise the lipid sphingomyelin
If ASM is absent or not functioning properly, sphingomyelin accumulates within the cell, eventually causing cell death and the malfunction of major organ systems.
tay sachs disease
Progressive deterioration of nerve cells and of mental and physical abilities that commences around six months of age and usually results in death by the age of four.
Gangliosides , cell membrane components, accumulate in the brain’s nerve cells
Functional Hexosaminidase-A is absent from lysosymes
Homocystinuria
Mutations in the CBS gene
Cystathionine beta-synthase. This enzyme acts in a chemical pathway responsible for converting the amino acid homocysteine to a cystathionine.
As a result of this pathway, other amino acids, including methionine, are produced.
Mutations in the CBS prevent homocysteine from being used properly. As a result, this amino acid and toxic by-products substances build up in the blood.
types of enzymes
oxidoreductases 2= transferases 3= hydrolases 4= lyases 5= isomerases 6= ligases
TRANSFERASES
Transferases are enzymes that catalyse the movement of a functional group from one molecule to another. These functional groups are very diverse can include phosphate, methyl and glycosyl groups.
example: kinases
LYASES
Lyases catalyse lysis reactions that generate a double bond. These are a type of elimination reaction but are not hydrolytic or oxidative. The reverse reaction catalyses an addition reaction, where a substrate is added to a double bond. These are often referred to as synthase enzymes.
pyruvate carboxylase
ISOMERASES
Isomerases are enzymes that can catalyse structural changes within a molecule. There is only one substrate and one product with nothing gained or lost, so they represent only a change in shape. The diagram shows a simple example of this sort of reaction.
LIGASES
Ligases are responsible for the catalysis of ligation; the joining of two substrates. Usually, chemical potential energy is required, so the reaction is coupled to the hydrolysis of a diphosphate bond in a nucleotide triphosphate such as ATP.
HYDROLASES
Catalyse hydrolysis; the breaking of single bonds through the addition of water.
Huge variety of hydrolase enzymes. eg, the digestive enzymes that are classified based on their target.
They are termed exo or endo depending on where they cut. Endo enzymes cut in the middle of the chain, whereas exo enzymes cut at the end of the chain to release an individual monomer.
give some examples of digestive enzymes:
Proteases/ peptidases cleave peptide bonds between amino acids in order to breakdown proteins
- Lipases break down lipids into fatty acids and glycerol by cleaving ester bonds
- Nucleases cleave phosphodiester bonds between nucleotide subunits in nucleic acids
