catabolism of protein and amino acid nitrogen Flashcards
(22 cards)
Biosynthesis of urea
- transamination
- oxidative deamintaion of glutamate
- ammonia transport
- reactions of urea cycle
Retards ubiquitination A. Asp,arg B. Met, ser C.Iso, Leu D.Val,Pro
B
Asp, Arg-accelerates
Only amino acid that undergoes oxidative deamination at an appreciable rate in mammalian tissues A.alanine B.glutamic acid C.glutamine D.glutamate
D
Formation of ammonia from a-amino groups occurs mainly by L-glutamate
Serves as carrier of amino groups during transamination
Pyridoxical phosphatey
Formed during transfer of amino nitrogen to a-ketoglutarate
L-glutamate
Conversion of a-amino nitrogen to ammonia by glutamate amintransferase and GDH A. Transdeamination B. Urea cycle C. Alanine formation D. Oxidative deamination
A.
What function in the brain is impaired due to depletion of a-ketoglutarate?
TCA in neurons.
(Ammonia reacts with a-ketoglutarate to form glutamate
Plays a major role in ammonia detoxification and acid-base homeostasis
A.glutamine synthase
B.glutamate synthase
A.
Glutamine increases in metabolic acidosis and decreases in metabolic alkalosis
Major end product of nitrogen catabolism in humans
Urea
Which of the following does not play a major metabolic role in urea synthesis of mammals A.ornithine B.citruline C.glutamine D.arginosuccinate
C.
No net lossor gain of a,b,d and arginine
Functions solely as an enzy,e activator in synthesis of urea
N-acetylglutamate
Rate-limiting enzyme of urea cycle
Carbamoyl phosphate synthase I
Carbamoyl phosphate plus ornithine forms A. Fumarate B. Aspartate C. Citrulline D. arginine
C.
Formation of ornithine and metabolism of citrulline occurs in cytosol
Citrulline plus Aspartate forms A. Fumarate B. Ornithine C. Arginine D. Arginosuccinate
D. Provides second nitrogen of urea
Cleavage of arginosuccinate forms
Arginine and fumarate
Catalyzed by arginosuccinate lyase
Trnasamination of oxaloacetate by glutamate aminotransferase reforms A. Aspartate B. Fumarate C. Citrulline D. Arginine
A.
Releases urea by hydrolytic cleavage of guanidino group of arginine
Liver arginase
Ornithine and lysine are potent inhibitors
Precursor of muscle relaxant nitric oxideA. Aspartate
B. Fumarate
C. Citrulline
D. Arginine
D
Defect in carbamoyl phosphate syntthase I causes
Hyperammonemia type I
Defect in ornithine transcarbamyolase
Hyperammonemia type 2
Syndrome caused by mutation of ORNT 1 gene
HHH syndrome
Hyperornithemia, hyperammonemia, homocitrulinuria
Technique of choice for screening neonates for inherited metabplic diseases
Tandem mass spectrometry
