Pyridoxal Phosphate in Aminotransferases

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What is the coenzyme form of pyridoxine required for the enzyme's activity?

Amino acid

Vitamin B6

Pyridoxal phosphate (correct)

Pyridoxine

What is the function of pyridoxal phosphate in aminotransferases?

Final transporter of amino groups

Initial donor of amino groups

Intermediate carrier of amino groups (correct)

Terminal acceptor 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 (correct)

Peptide bond

Hydrogen bond

Disulfide bond

What is the form in which amino groups are transported in blood to the liver?

Glutamine, glutamate, and alanine Signup and view all the answers

Where are the amino groups of amino acids from dietary proteins and cellular proteins incorporated into?

Glutamate Signup and view all the answers

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 Signup and view all the answers

What is the product of the transamination reaction between glutamate and pyruvate in muscle?

Alanine and α-ketoglutarate Signup and view all the answers

What is the purpose of the Glucose-Alanine Cycle?

To transport amino groups from muscle to liver Signup and view all the answers

What is the enzyme involved in the transamination reaction between alanine and α-ketoglutarate in the liver?

Alanine aminotransferase Signup and view all the answers

What is the fate of pyruvate produced in the liver through gluconeogenesis?

It is transported to muscle and converted to alanine Signup and view all the answers

What is the purpose of glutamine synthetase in extrahepatic tissues?

To convert glutamate to glutamine Signup and view all the answers

What is the byproduct of the deamination of glutamate in the liver?

NH4+ and α-ketoglutarate Signup and view all the answers

What is the term used to describe the connection between the urea cycle and the citric acid cycle?

Krebs bicycle Signup and view all the answers

Where are the enzymes fumarase and malate dehydrogenase also present as isozymes?

Cytosol Signup and view all the answers

What is the product of the hydration of fumarate in the cytosol?

Malate Signup and view all the answers

What is one possible fate of oxaloacetate?

It can undergo transamination to aspartate Signup and view all the answers

At what two levels can the activity of the urea cycle be regulated?

At the level of enzyme synthesis and control by allosteric regulation Signup and view all the answers

What enzyme's rate of synthesis can control the activity of the urea cycle?

Carbamoyl phosphate synthetase I Signup and view all the answers

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 Signup and view all the answers

Why is a protein-free diet not a treatment option for deficient enzymes?

Because humans cannot synthesize essential amino acids Signup and view all the answers

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 Signup and view all the answers

What is a symptom of ammonia intoxication?

Tremor Signup and view all the answers

What is a possible reason for the toxic effect of ammonia?

A decrease in the formation of ATP by citric acid cycle Signup and view all the answers

What is a common symptom of hyperammonemia?

Lethargy Signup and view all the answers

What is the product of the cleavage of the aromatic ring of homogentisate?

4-maleylacetoacetate Signup and view all the answers

What is the name of the disease caused by a deficiency of phenylalanine hydroxylase or its tetrahydrobiopterin cofactor?

Phenylketonuria Signup and view all the answers

What is the end product of the reaction catalyzed by maleylacetoacetate isomerase?

4-fumarylacetoacetate Signup and view all the answers

Which enzyme is responsible for the hydrolysis of 4-fumarylacetoacetate to fumarate and acetoacetate?

Fumarylacetoacetase Signup and view all the answers

What is the characteristic of the urine in individuals with phenylketonuria?

Mousey odor Signup and view all the answers

What is the alternative pathway of phenylalanine metabolism in individuals with phenylketonuria?

Transamination with pyruvate Signup and view all the answers