Protein Metabolism Flashcards
What are amino acids
building blocks of proteins
Proteolysis
protein breakdown through hydrolysis of their peptide bonds
Enzymes that catalyze proteolysis
proteases
Where does protein synthesis take place?
ribosomes
key points of protein synthesis
Translation of mrna from transcription of a gene
Approximation of free amino concentrations in the body
Glutamine ~60%
Glutamate ~14%
Alanine ~4%
Where are amino acids typically found in the cell?
cytosol
What are the primary uses of free amino acids
processing other aminos
What is the glucose alanine cycle?
Converts alanine to pyruvate and ultimately glucose
What is the first step of breakdown of all amino acids?
removal of the nitrogenous alpha amine group (NH3+)
What is non oxidative deamination?
Loss of an amine group uses oxygen
What type of enzyme is required for non oxidative deamination?
dehydrogenase
Why is non oxidative deamination unique?
Only 2 amino acids go through it
Which two amino acids go through non oxidative deamination?
serine and threonine
Through the process of non oxidative deamination what are amine groups released as?
ammonia
Serine Deaminase
aka serine dehydratase
catalyzes the dehydrogenation of serine into pyruvate and ammonia (NH4)
Threonine Deaminase
aka theronine dehydratase
catalyzes the dehydrogenation of threonine into pyruvate and ammonia
Key difference between oxidative and non oxidative deamination
Oxidative deamination occurs via the oxidation of amine group amino acids whereas non oxidative deamination occurs via any other reaction
Oxidative deamination
Glutamate loses amine group and a H+
oxidized by NAD+ or NADP+
Transamination
transfer of amine groups to alpha ketoglutarate to form glutamate and alpha keto acid.
Most aminos (excluding glutamate, serine and threonine go through this process)
Aminotrasferase
Enzyme responsible for catalyzing the transamination of amino acids (ecluding glutamate, threonine and serine)
What is the most common fate of Alpha keto acids?
conversion to intermediates of carb and fat metabolism
Potential fates of alpha keto acids
pyruvate
acetyl coA
Acetoaceytl CoA
Succinyl CoA
Fumerate
Oxaloacetate
Where does glutamate transer its amine group?
pyruvate
what is formed when glutamate transfers its amine group?
Alpha ketoglutarate and alanine
Alanine Aminotransferase
catalyzes the conversion of glutamate and pyruvate to alpha ketoglutarate and alanine
Glutamine Synthetase
Glutamate reacts with ammonia group (and ATP) to form Glutamine +ADP + Pi + H+
how many glucogenic amino acids are there?
14
how many ketogenic amino acids are there? what are they?
2 (leucine, lysine)
how many glucogenic and ketogenic amino acids are there? what are they?
4 (isoleucine, phenylalanine, tryptophan, tyrosine)
What does the Urea Cycle begin with?
carbamoyl phosphate
What is Carbamoyl phosphate
Compound of high phosphoryl transfer potential formed by combining ammonia, bicarbonate and a phosphoryl group
Carbamoyl phosphate synthetase
Enzyme responsible for the formation of carbamoyl phosphate
how many ATP are expended in the formation of carbamoyl phosphate?
2
What is the only amino acid to donate an amine group in the urea cycle?
Aspartate
