What role do cofactors play in enzyme catalysed chemical reactions?

Question 1

Why are cofactors important

Answer 1

• Some enzymes can only function with a cofactor present.
  *

Question 2

What is a cofactor

Answer 2

• A non protein molecule!

Question 3

What do co factors do

Answer 3

• The modify the the structure of the enzyme is some way so the enzyme can function more effectively

Question 4

What is an example of the way a co factor works

Answer 4

• Amylase catalyses the break down of starch to maltose
• This reaction can only occur if the co factor Chloride ions (CL^-) ions are present

Question 5

What are the 3 types of co factors

Answer 5

• Prosthetic groups
• Coenzymes
• Activators

Question 6

What are prosthetic groups

Answer 6

• Prosthetic groups are molecules that form permanent attachments to an enzyme

Question 7

What is an example of a prosthetic group

Answer 7

• Haemoglobin

Question 8

What is haemoglobin

Answer 8

Haemoglobin has

• 4 polypeptide chains
• which are joined together by Disulfide bonds
• At the centre of each polypeptide chain is an iron containing group called haem (A prosthetic group)
• Each of these Haem prosthetic groups has an iron ion Fe2+
• As each Iron ion can bind with one molecule of oxygen (O2), there are 4 molecules of oxygen
• This protein combines with the prosthetic group forming a cojugated protein.

Question 9

What is the metabolic role of haemoglobin

Answer 9

• Haemoglobin picks up O2 in the lungs forming oxyhaemoglobin
• Oxyhaemoglobin is broken down (dissacociates) in the tissues giving up its oxygen, and then reverts back to haemoglobin.

Question 10

What cofactor does carbonic acid collaborate with

Answer 10

Carbonic anhydase collaborates with a zinc based co factor (ZN²⁺)

Question 11

What role does carbonic anhydrase play in the blood?

Car bon ic

An hy drase

Answer 11

• Carbonic anhydrase plays a critical function in the blood…
• Carbonic anhydrase catlyses the combination of water and dioxide
• Forming carbonic acid
• Which enables carbon dioxide to be transported in the blood

Question 12

What are co enzymes

Answer 12

• Co enzymes are smal nonprotein organic molecules are not permanently attached to the enzyme (Unlike prosthetic co factors)

Question 13

What do co enzymes do?

Answer 13

• Co enzymes help certain enzymes and substrates to bond with each other
• NB: Where a co enzyme is needed to catlyse a reaction, the enzyme can only function when it is present.

Question 14

What are many enzymes derived from

Answer 14

• Vitamins
  
  • e.g. The coenzyme NAD is derived from the vitamin nicotinic acid

Question 16

What is NAD the coenzyme for

Answer 16

• It is the coenzyme for a number of dehydrogenase enzymes
• It acts as a hydrogen receptor

Question 17

What are activators

Answer 17

• Activators are inogranic metal ions
  
  • e.g. Magnesium Mg²⁺, Iron Fe²⁺, Calcium Ca²⁺

Question 18

What is the function of activators

Answer 18

• Activators form a temporary attachment to the enzyme…and change the active site….to increase the probability that a reaction will occur

Question 19

What are examples of activators

Answer 19

• Protein synthesis cannot occur without magnesium present as a co factor
• Muscle contraction and nerve impulses cannot happen without calcium present as a co factor

Question 20

Where do most metal activators come frome

Answer 20

• Diet