Enzymes Flashcards
Enzyme graph
1- initially lots of substrate and empty active sites
Many E-S complexes can form speeds up reaction
Reaction starts of fast
2- less substrate and more product
So it’s more difficult for E-S complexes to form
Reactions slows down
3- no more substrate
So no more E-S complexes
Reaction stops
Rate of reaction formula
Volume/time=rate of reaction
Effect of temperature graph (volume of product)
• Enzymes have more kinetic energy at 37°
• so more E-S complexes
• faster reaction
• converse
Effect of temperature (rate of reaction)
• as temperature ^ the rate ^ due to more Ek
• optimum temperature = most E-S complexes form
•temp ^ rate ⬇️ as enzymes are denatured
• tertiary structure changed so no E-S complexes can form
Effect of pH (volume of produced)
• ^ as H+ ions are attracted to the amino acids of enzymes
• ionic and hydrogen bonds in the tertiary structure are disrupted
• active sites of enzymes denature
• fewer E-S complexes form
• reaction incomplete
• for pH 7 it’s converse
Effect of pH (rate of reaction)
• active site denatures so no E-S complexes form
• optimum pH
• Active site denatures which means no E-S complexes form
Effect of enzyme concentration (volume of product)
2 moles catalase:
• faster reaction
• ^ enzymes = ^ E-S complexes
• accept converse
Effect of enzyme concentration (rate of reaction)
• enzyme conc^ rate of reaction ^
• in direct proportion
• as more E-S complexes form
• rate is only limited by amount of substrate
More active sites= more fast reactions
Effect of substrate concentration (volume of product)
2 moles substrate:
• faster reaction
• ^ substrate ^ E-S Complexes
• Accept converse
Effect of substrate concentration (rate of reaction)
• as substrate conc ^ rate ^
• directly proportional
• more E-S complexes are formed
• rate is only limited by amount of enzyme
What are enzyme inhibitors?
They slow down catalysed reactions
What are competitive inhibitors?
Molecules with a similar shape to a substrate. They act as active sites and prevent E-S complexes from forming
Competitive inhibitors (volume of product)
Slows reaction
C.I binds to active site
Prevents E-S complexes
Competitive inhibitors (rate of reaction)
You can increase the rate of product formation by adding more substrate
The additional substrate will outcompete the inhibitor
What are non-competitive inhibitors?
•Molecule that attach to the allosteric binding site (not active site) on an enzyme
•This changes the tertiary structure of the active site permanently
•active site is no longer complementary
•No E-S complexes can form
Non-competitive inhibitor (rate of reaction)
• you can’t increase the rate of product formation by adding more substrate
• the enzyme are out of action. Add more enzymes to overcome this
Non-competitive inhibitor (volume of product)
• reaction slows and doesn’t complete
• NCI binds to allosteric binding site
• active site changes shape
• no E-S complexes can form
What is the primary structure of protein?
The sequence of amino acids which is determined by genes
What is the secondary structure of proteins?
Hydrogen bonds form between the amino acids in the chains. This makes it either an alpha helix or a beta pleated sheet.
What is the tertiary structure of protein?
The folded chain of amino acids are further folded. Hydrogen and ionic bonds form between different parts of the polypeptide chain. This folding forms the polypeptide into a 3D shape.
What is the quaternary structure of protein?
Multiple polypeptides bonded e.g) haemoglobin
What is activation energy ?
The minimum amount of energy that is required for molecules to collide with each other
What does high kinetic energy do in a catabolic reaction ?
Strains the bonds so the substrate molecules breaks more easily
Anabolic reactions
Brings substrates closer together. Lowers the activation energy needed for the reaction to take place reducing repulsion between molecule so they bond more easily.
Structural proteins
Structural proteins are physically strong. They consist of king polypeptide chains lying parallel to each other with cross links between them. Eg) Keratin
Collagen has three polypeptide chains which makes it strong. This is a great supportive tissue in animals.