coenzymes, cofactors and prosthetic groups Flashcards
what is a coenzyme
an organic molecules containing cofactors
some coenzyme are permanently bound to the enzyme they assist, often in or near the active site
some coenzyme only bind temporarily during the reaction
their functions is to bind to the active site of an enzyme to make it complementary to the substrate participate in catalysis but are not substrate of the reaction - carrying electrons or chemical groups between enzymes
what is an source for coenzymes and give an example
vitamins are an important source of coenzymes.
vitamins in the B vitamin group are used in the production of the important coenzymes
summary of coenzymes
organic non-protein cofactors. coenzymes contribute to enzyme-catalysed reactions by accepting or donating hydrogen ions or chemical groups
cofactors
inorganic ions that help enzymes function properly
help to stabilise the structure of the enzyme or may actually take part in the reaction at the active site e.g.chloride ions act as a cofactor for amylase - this means that in order for amylase to be able to digest starch into maltose, chloride ions must be present
substances other than substrates and inhibitors that interact with enzymes
some enzymes can only function properly if another non-protein substance is present
for example, some enzymes are inactive until they combine with a non-protein substance that changes their tertiary structure (allowing the active site to bind correctly with the substrate)
examples of co-factors
amylase and chloride ions
amylase breaks down starch into maltose, requires chloride ions as a co-factor to activate and function properly
carbonic anhydrase and zinc ions
carbonic anhydrase speeds up the conversion of carbon dioxide and water to carbonic acid. zinc acts as a co-factor that stabilises the enzyme’s active site
NAD⁺ in Glycolysis:
During glycolysis, NAD⁺ accepts hydrogen atoms from intermediates, forming NADH. This allows the continuation of ATP production.
examples of coenzymes
Pathothenic acid is a key component of coenzyme A - coenzyme required for the oxidation of pyruvate during the link reaction that occurs between the glycolysis and Kerbs cycle stages of respiration
Nicotinic acid is used to produce the coenzyme NAD and NADP (coenzymes required in many different metabolic reactions, including many of the reactions that take place during photosynthesis and respiration)
vitamin B1 (riboflavin) used to produce the coenzyme FAD (a coenzyme required in the Kerbs cycle during respiration)
A student conducted an experiment on amylase activity in the presence and absence of chloride ions. They observed that the enzyme showed minimal activity when the chloride ions were removed. Explain why the enzyme activity was reduced in the absence of chloride ions.
Chloride ions act as cofactors for amylase, enabling it to maintain its active conformation and properly bind to the substrate. Without chloride ions, the enzyme’s active site may not be properly stabilized, leading to reduced catalytic efficiency. Thus, the absence of chloride ions results in decreased enzyme activity.
what is a prosthetic group
permanently attached to the enzyme
a non-protein group
example of prosthetic group
haemoglobin contains a prosthetic haem group with contains iron (Fe 2+), permanently bound to the molecule, which serves as a means of binding oxygen
