4 - Enzymes Flashcards
Active Site
Indented area on a surface of an enzyme with a complementary shape to the substrate.
The tertiary structure of the active site is crucial as its shape is complementary to the shape of the substrate molecule. So each enzyme is highly specific.
Catalyst
Chemical that speeds up the rate of reaction and remains unchanged and unused by the end of the reaction.
Extracellular
Intracellular
Inside the cell
Outside the cell
Metabolic
The chemical reactions that take place within a living cell
Product
Molecules produced from substrate molecules by an enzyme catalysed reaction
Substrate
Molecules that are altered by enzyme-catalysed reactions
Anabolic and Catabolic
The chemical reactions required for growth are anabolic reactions and they are catalysed by enzymes. Energy is released from large organic molecules or through metabolic pathways consisting of catabolic reactions
Cofactor
A substance that has to be present to ensure the enzyme catalysed reaction takes place at the appropriate rate. SOME cofactors are part of the enzyme structure (prosthetic group) and others form temporary associates with the enzyme (coenzyme)
Enzyme-substrate complex
A complex formed by temporary binding of the enzyme and substrate molecules during an enzyme catalysed reaction.
The Lock and Key Hypothesis
This is where the active site and the substrate molecule fit because the tertiary structure of the enzymes active site is complementary to the substrate.
The Induced Fit Hypothesis
The active site of the enzyme is not a fixed structure, but there’s substrate molecule that it induces changes shape giving a good fit.
Enzymes lower the activation energy of a reaction AS THEY ….
Enzymes lower the activation energy of a reaction as they increase the kinetic energy of the molecule making a move model making the most successful collisions and then they react together.
Enzyme product complex
Enzyme molecule with product molecules in its active site that I joined temporary together by non-covalent forces.
Enzyme substrate complex
Enzyme molecule with substrate molecules in its active site that are joined together temporarily by non-covalent forces.
The effect of temperature on enzyme activity
If a substance is heated, then there be more energy in the form of heat causing a molecules to move faster therefore there will be increased collisions.
Denatured
When an enzyme becomes denatured its shape becomes reversibly changed and therefore the substrate can no longer be complimentary.
pH
A buffer is something that research changes in pH. Enzymes work within a narrow range of pH
Low pH
Enzymes that work extra cellular have an ultimate pH that is not seven. For example enzymes within the stomach have a low pH as hydrochloric acid is needed.
Effect of changing substrate concentration
As a substrate is added and its concentration increases the rate of reaction increases. This is because more enzyme-substrate complexes can form meaning of product molecules are formed. Is the limiting factor as when it increases the rate of reaction increases.
Competitive inhibition
Inhibition of an enzyme inhibitor molecule has a similar shape to the substrate molecule and competes with the substrate for the enzymes active site. It blocks the active site and prevents the formation of an enzyme substrate complex.
Non competitive inhibition
Inhibition of an enzyme with a competitor molecules attached to the part of the enzyme, but not the active site this changes the shape of the active site which prevents the ES complex forming as the active site is no longer complementary in shape to the substrate molecule.
Inhibitor
A substance that stops or reduces a reaction
End product Inhibition
After the reaction has completed product molecules and missed a tightly bound to the enzyme so that it cannot produce more. More product than needed such radiation is known as negative feedback.
Poisons and medical drugs
Snake venom contains a chemical that inhibits enzymes
Cyanide is highly toxic as it inhibits aerobic respiration. It also inhibits catalase
ACE inhibitors I used to lower blood pressure in patients with hypertension and treat heart failure.
