30 Questions
What is the coenzyme form of pyridoxine required for the enzyme's activity?
Pyridoxal phosphate
What is the function of pyridoxal phosphate in aminotransferases?
Intermediate carrier of amino groups
What type of linkage is formed between pyridoxal phosphate and the ε-amino group of a Lys residue?
Aldimine (Schiff base) linkage
What is the form in which amino groups are transported in blood to the liver?
Glutamine, glutamate, and alanine
Where are the amino groups of amino acids from dietary proteins and cellular proteins incorporated into?
Glutamate
What is the result of the formation of a Schiff base between pyridoxal phosphate and the amino group of the amino acid?
Release of the enzyme
What is the product of the transamination reaction between glutamate and pyruvate in muscle?
Alanine and α-ketoglutarate
What is the purpose of the Glucose-Alanine Cycle?
To transport amino groups from muscle to liver
What is the enzyme involved in the transamination reaction between alanine and α-ketoglutarate in the liver?
Alanine aminotransferase
What is the fate of pyruvate produced in the liver through gluconeogenesis?
It is transported to muscle and converted to alanine
What is the purpose of glutamine synthetase in extrahepatic tissues?
To convert glutamate to glutamine
What is the byproduct of the deamination of glutamate in the liver?
NH4+ and α-ketoglutarate
What is the term used to describe the connection between the urea cycle and the citric acid cycle?
Krebs bicycle
Where are the enzymes fumarase and malate dehydrogenase also present as isozymes?
Cytosol
What is the product of the hydration of fumarate in the cytosol?
Malate
What is one possible fate of oxaloacetate?
It can undergo transamination to aspartate
At what two levels can the activity of the urea cycle be regulated?
At the level of enzyme synthesis and control by allosteric regulation
What enzyme's rate of synthesis can control the activity of the urea cycle?
Carbamoyl phosphate synthetase I
What is the purpose of supplementing the diet with benzoate and phenylacetate in Carbamoyl phosphate synthetase I and ornithine transcarbamoylase deficiency?
To excrete excess nitrogen in the form of hippurate and phenylacetylglutamine
Why is a protein-free diet not a treatment option for deficient enzymes?
Because humans cannot synthesize essential amino acids
What is the difference between essential and non-essential amino acids?
Essential amino acids are provided in the diet, while non-essential amino acids are synthesized by humans
What is a symptom of ammonia intoxication?
Tremor
What is a possible reason for the toxic effect of ammonia?
A decrease in the formation of ATP by citric acid cycle
What is a common symptom of hyperammonemia?
Lethargy
What is the product of the cleavage of the aromatic ring of homogentisate?
4-maleylacetoacetate
What is the name of the disease caused by a deficiency of phenylalanine hydroxylase or its tetrahydrobiopterin cofactor?
Phenylketonuria
What is the end product of the reaction catalyzed by maleylacetoacetate isomerase?
4-fumarylacetoacetate
Which enzyme is responsible for the hydrolysis of 4-fumarylacetoacetate to fumarate and acetoacetate?
Fumarylacetoacetase
What is the characteristic of the urine in individuals with phenylketonuria?
Mousey odor
What is the alternative pathway of phenylalanine metabolism in individuals with phenylketonuria?
Transamination with pyruvate
Learn about the role of pyridoxal phosphate, a coenzyme form of vitamin B6, in the mechanism of aminotransferases. Understand how it functions as an intermediate carrier of amino groups and binds to the enzyme's active site.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
