25 September 2014

The Urea Cycle

Big Picture:
An Ammonium Ion combines with Bicarbonate and Aspartate to form Urea
How is the Urea Cycle turned on and off? What might prevent the urea cycle from excreting Nitrogenous waste even when the amount of waste is very high?




The Control step:
Bicarbonate and NH4 Combine to form Carbomoyl Phosphate at the expense of 2 ATPs
Carbomoyl Phosphate Synthetase 1 (CPS1) catalyzes the reaction
  If N-AcetylGlutamate (NAG) is present then CPS1 is active
  NAG is formed by combining Acetyl-CoA with Glutamate
  THERE MUST BE LOTS OF ACETYL-COA OR THE REACTION WON’T HAPPEN
  Low energy state can prevent the Urea Cycle by not having acetyl-CoA

No comments:

Post a Comment