Enzymes

• How does a change in pH affect enzyme structure


  change in H+ concentration

  H+ ions interact with polar and charged r groups in the tertiary structure

  this breaks the bonds/ interaction between r groups leading to loss of tertiary structure
• What is the temperature coefficient? (Q10)


  A measure of how much the reaction rate increases with a 10 degrees increase
• What are metabolic reactions


  The sum of all reactions in an organism
• Name the 2 models

  lock and key, induced fit
• Name 2 extracellular enzymes


  amylase and trypsin
• How are the enzymes in extromphiles adapted?


  enzymes are more stable ( have more bonds in the tertiary structure)

  More resistant to denaturation by high heat.
• Define the term denaturation


  loss of active site shape
• What are enzymes effect on the activation energy of a reaction


  enzyme lowers activation energy
• What is the difference between the lock and key theory and the induced fit 


  Lock and key= rigid no movement

  induced fit= slight movement of active site to allow better binding to substrate
• Explain why an increase in substrate concentration increases rate of reaction


  Higher successful collision rate

  between active site and the substrate

  forming more enzyme substrate complexes
• How are the enzymes i organisms that live in cold environments adapted 


  enzymes are more flexible hence less stable

  Can move more in loew KE environment to bind
• name the structure where the enzyme and substrate are bound together 


  enzyme substrate complex
• What are catabolic reactions 


  breaking down molecules
• What are anabolic reactions 


  building up larger molecules
• Explain how high temperatures can denature enzymes


  High temperatures lead to more vibrations

  too much vibration breaks the bonds that holds the protein together
• Name an intracellular enzyme


  Catalse
• Explain how an increase in temperature of temperature increases enzyme activity


  increase in temperature increases particles kinetic energy

  particles move faster and collide more often

  more successful collisions between active site and substrate
• What does hydrogen peroxide break down into?


  water and oxygen
• Define competitive inhibitation


  inhibitor and substrate molecules will compete to bind to the active site
• Describe the process of competitive inhibition


  an inhibitor ( a molecule that has a similar shape to the substrate of an enzyme) can fit into the active site of the enzyme

  This blocks the substrate from entering the active site, preventing the enzyme from catalysing the reaction

  The enzyme cannot carry out its function and is said to be inhibited

  Most competitive inhibitors bind temporarily so most are reversible
• What happens to the rate of reaction in competitive inhibition


  the rate of reaction is decreased- degree of inhibition depends on concentration of substrate/inhibitor/enzyme
• What happens to the Vmax in the rate of reaction of competitive inhibitor


  is not changed- effects can be overcome by adding more substrate- rate of reaction will continue to rise and Vmax can still be reached
• Give an example of competitive inhibitors


  statins inhibits an enzyme used in the synthesis of cholesterol, hence they are prescribed to lower cholesterol
• define non- competitive inhibition

  inhibitor does not compete with substrate for the active site
• Describe the process of non- competitive inhibition

  The inhibitor binds to an alternative site called the allosteric site

  This causes changes in the tertiary structure of an enzyme, meaning the active site changes shape

  The active site is no longer complementary to substrate so they cannot bind

  No enzyme substrate complexes can form

  the enzyme is unable to carry out its function so is said to be inhibited
• What happens to the rate of reaction in non-competitive inhibition


  Increasing the concentration of an enzyme or substrate will not overcome the effect of a non-competitive inhibitor, the rate will not continue to rise

  Increasing the concentration of inhibitor will decrease the rate of reaction further as more active sites become unavailable.
• Give an example of Non-competitive inhibition


  cyanide ions decrease the action of catalase even at high concentration of hydrogen peroxide
• What is a cofactor


  any inorganic ion that increases the activity of an enzyme. It is temporarily bound to the enzyme
• How are cofactors obtained


  through dietary minerals (iron, chloride, calcium and zinc ions)
• Give an example of a cofactor 


  CL- is the ion that is a cofactor for amylase (necessary for the formation of a correctly shaped active site)
• What is a coenzyme


  a non- protein organic molecule that is needed to allow the enzyme to function. it is temporarily bound to the enzyme
• Where are coenzymes obtained from?


  dietary vitamins
• Give examples of coenzymes


  Vitamine B5 is used to make coenzyme A, which is essential in the breakdown of fatty acids and carbohydrates in respiration
• What is a prosthetic group


  tightly bound cofactors that are permanent features of the protein
• What is the prosphetic group of haemoglobin 


  a haem group which contains iron (Fe2+) permanently bound to the molecule which serves as means of binding oxygen
• Describe the action of coenzymes/cofactors/prosphetic groups 


  bind to the enzyme (active site or allosteric site) and either causes a change in the tertiary structure- the shape is changed of the active site and allows a substrate to bind, reduces activation energy required for reaction
• What is end-product inhibition


  the term used for enzyme inhibits that occurs when the product of a reaction acts as an inhibitor to the enzyme that produces it, excess products are not made, and resources arent wasted
• Give an example of end product inhibition


  respiration
• What are (inactive precursor enzymes) 


  enzymes that are produced in an inactive form which often need to undergo a change in shape (tertiary structure), particularly to the active site to be activated which can be achieved by the addition of a cofactor
• Give the equation in order to create a holoenzyme (activated enzyme)


  Apoenzyme (inactive precursor enzyme) + cofactor/coenzyme-> holoenzyme