Final - AA metabolism Flashcards
(23 cards)
In amino acid catabolism, what part of the a.a. do we remove/where does it go? & what part do we utilize?
Remove Nitrogen (amine group) which gets excreted as Urea
Utilize the C-skeleton by: oxidation in Citric Acid Cycle, conversion to glucose (gluconeogenesis), and conversion to fat (via acetyl-CoA)
(135)
What does the removal of the amino group on an amino acid require? (3 steps)
Transamination
Oxidative Deamination
Urea synthesis
(135)
What is the alpha-keto form of Aspartate? of Glutamate? of Alanine?
Aspartate = Oxaloacetate (OA = KC intermediate)
Glutamate = alpha-ketoglutarate (KC intermediate)
Alanine = Pyruvate
(136-137)
What is the amino acid form of oxaloacetate? of alpha-ketogluterate? of Pyruvate?
Oxaloacetate = aspartate
Alpha-ketogluterate = glutamate
Pyruvate = alanine
(136-137)
What is the purpose of transamination?
Interconverting amino acids
Shuttling -NH3 groups to glutamate and aspartate (which sets things up for entry into the urea cycle)
(137)
All clinical lab tests use what pair of substrate/product and what coenzyme?
Glutamate and alpha-Ketogluterate as substrate/product
Pyridoxal Phosphate = coenzyme
(137)
What is the purpose of oxidative deamination?
Production of NH4+ (ammonia)
139
What are the products of oxidative deamination of glutamate?
NH4 and alpha-Ketogluterate
139, 136
The Urea Cycle (a.k.a. Krebs-Henseleit Cycle) is most important in what part of the body?
Liver
*=site of urea synthesis
(141)
Which enzyme regulates the urea cycle?
Carbamoyl Phosphate Synthetase
142
What is the last enzyme in the Urea cycle?
Arginase
(bottom part of Arginine becomes urea)
(142)
True or False: Alanine is a non-useful amino acid to transfer N+ to the liver and kidneys for excretion?
False; Alanine IS a useful amino acid to transfer N+ to kidneys and liver
(143)
After removal of amino groups, the alpha-Keto acids are available for what?
1) Synthesis via gluconeogenesis or fatty acid & ketone synthesis
2) Oxidation
(144)
Which type of amino acids must be converted to Acetyl-CoA?
Which amino acids are they?
Ketogenic
Leucine and Lysine
(144)
What is the name for amino acids that are converted to pyruvate or other KC intermediates?
How many are there?
Glucogenic amino acids
18/20 a.a. are glucogenic
*alanine, aspartate, glutamate, glutamine … etc
(144)
What does a positive nitrogen balance indicate?
What does a negative nitrogen balance indicate?
+ balance requires a net synthesis of tissue proteins (growth period/pregnancy)
- balance requires a net catabolism of tissue proteins (starvation, decrease CHO, increase N+ extreted0
(146)
Does intake of CHO favor a more positive N-balance or a negative one?
Positive (protein sparing effect)
146
What is the result of pyruvate undergoing transamination?
Alanine
147
What do you get when oxaloacetate undergoes transamination?
Aspartate
147
Which amino acid pathway conversion is limited in Phenylketonuria (PKU)? What is the resulting effect?
Limited conversion of phenylalanine to tyrosine. Phe is converted to ketone by-products (phenylpyruvate or phenylketones) = can cause retardation and death by age 30
(150)
What amino acid abnormal pathway disorder occurs because of decreased tyrosinase?
Albinism (decreased melanin)
150
Which amino acid abnormal pathway disease is correlated with decreased homogentisate oxidase?
Alcaptonuria
-urine turns black
-causes problem in tyrosine/phe catabolism
(150)
What is the defective enzyme in PKU (phenylketonuria), Albanism, Alcaptonuria?
PKU = phenylalanine hydroxylase
Albinism = tyrosinase
Alcaptonuruia = homogentisate oxidase
(150)
