regulation of HK 1

Question 1

How many isozymes are there?

Answer 1

same function, but maybe different structure , so that different tissues can regulate these enzymes differently
5 and here are the important ones :
- HK 1 and in the skeletal muscle and brain
- HK 4 in the liver

Question 2

HK 1, how is inhibited

Answer 2

• inhibited allosterically by G6P at C and N terminus
• G6P is a CI for ATP at these locations
  why? The G6P phsphte , when bound in ATP binding site overlaps the area where ATP a/b Phsphtes would be

Question 3

How does HK1 overcome G6P’s inhibition?

Answer 3

• phosphate ion concentration
• in a cell dont wnat too much phosphate because if calcium phosphate forms, it will crystalize out.
• but if free phsphtes (inorganic phsphtes) bind to these spots, it signals to the cell that there is a need for ATP production (ADP + P)

Question 4

G6P is the immediate product of…

Answer 4

HK, so it causes substrate level inhibition

Question 5

HK1 has a small Km value

Answer 5

this tells us that the enzyme is very efficient.
- bc you reach Km faster