Nitrogen Waste and Urea Cycle Flashcards
What comes from the muscles during the fasting state?
Alanine
Glutamine
When is the urea cycle running?
During both the fasted and the fed state
First step in the urea cycle?
CO2 + NH4+ -> carbamoyl phosphate
What enzyme catalyzes CO2+NH4+?
Carbamoyl Phosphate Synthetase I
Where does the NH4+ come from to create carbamoyl phosphate?
Glutamate -> alpha-KG +NH4+
What does carbamoyl phosphate react with?
Ornithine
What reaction does ornithine transcarbamylase catalyze?
Ornithine + carbamoyl phosphate -> Citrulline
What does citrulline react with making what?
Aspartate making arginosuccinate
What enzyme catalyzes citrulline + aspartate?
Arginosuccinate synthetase
Where do the two ammonia come from in the urea?
Aspartate
Free ammonia that came off glutamate
Where do these reactions take place?
Liver but in the mitochondria everything up to citrulline which enters the cytosol
What does aspartate transaminase do?
Converts OAA to aspartate
What diseases show elevated AST and ALT enzymes?
Hepatitis A and B
Acetaminophen
Shock
What happens in alcoholic liver disease?
AST>ALT 2:1 ratio
Most common urea cycle deficiency?
Ornithine transcarbamylase (OTC)
