Nitrogen Flashcards
What are the main nitrogen containing molecuels in the body? (IMPORTANT)
Nucleic Acid Nucleotides Protein Amines Haem-containing groups
What is transamination?
When the amine group is transferred from one amino acid to a ketoacid to produce a new amino acid & ketoacid
Transamination is reversible what does this say about aminotransferases?
Theyre involved in amino acid breakdown & synthesis
What Cofactor do aminotransferases rely on to transfer the Amine group
Pyridoxal Phosphate Cofactor
(PLP) derived from vitamin B6
When do amino acids undergo oxidative catabolism?
- When left over from protein synthesis
- When excess from diet
- When carbs are absent so muscle proteins are used for energy
How are proteins broken down to amino acids?
Proteins -> Peptides in stomach/small intestine by peptides
Peptides -> amino acids in small intestine
What happens to amino acids?
Broken to carbon skeletons & Ammonia
What are the 2 types of carbon skeleton?
Glucogenic
Ketogenic
What happens to glucogenic ones?
They enter gluconeogensis as oxaloacetate. Sometimes via the CAC to become oxaloacetate
What happens to ketogenic ones?
They become Acetyl-CoA so cant enter gluconeogenesis, they become ketone bodies.
What happens to the Ammonia from amino acids?
Used for biosynthesis of important nitrogen containing compounds
Any excess forms carbomoyl phosphate and enters the urea cycle
How is ammonia transported in the blood?
As alanine or glutamine
Why isnt ammonia just transported as glutamate?
BEcause its -ve so cant cross membranes
What happens to excess pyruvate in exercising muscle?
Some is converted to alanine by an amino transferase reaction with glutamate (made from muscle protein breakdown)
What ahppens to alanine made in muscles?
TRansported to the liver
Aminotransferase reaction produces pyruvate & glutamate again
- Pyruvate enters gluconeogenesis & as Glc is returned to muscle
- Glutamate enters urea cycle.
