transanimation Flashcards
what happens in amino acid metabolism
excess ammonia generated in extrahepatic tissues by catabolism of amino acids and nucleic acids
transported in the bloodstream amino groups to the liver where they are converted to urea for excretion
what transports amino groups generated in muscle
alanine
what degraded amino acids
muscle
what are amino groups collected as
glutamate
what is glutamate converted to
alanine by action of alanine aminotransferase
how does alanine take amino groups to the liver
via the bloodstream
where does alanine aminotransferase convert alanine to glutamate
cytosol of hepatocytes
what releases NH4 and where
glutamate dehydrogenase into the mitochondria
what is the role of glutamine
transports ammonia in the blood to the liver where processed for excretion
what happens to glutamine
in the mitochondria, glutaminase converts it to glutamate with the release of NH4
what happens to NH4
directly excreted - forms salt with metabolic acids attempt to counteract acidosis
what happens in the cytosol of hepatocytes in transanimation
amino groups form L-amino acids are transferred onto a-ketoglutarate to form glutamate
the amino acid becomes the corresponding a-ketoacid
what is the transamination reaction catalyzed by
specific transaminases (aminotransferases)
what happens to glutamate
transported to the mitochondria of hepatocytes, where the amino group is removed to form NH4+
what is transamination dependent on
the transaminase cofactor, pyridoxal phosphate
what is pyridoxal phosphate
an intermediate carrier of amino groups between amino acid and enzyme
what does pyridoxal phosphate do
accepts amino group from amino acid amd donates amino group to a-ketoglutarate
what is the role of transamination reactions
collect amino group from amino acids in the form of L-glutamate
what pathways do glutamate act as an amino donor in
biosynthetic pathways and excretion pathways
how is the excretion of amino acids done
glutamate is transported to the mitochondria where glutamate dehydrogenase removes amino group in an oxidative deamination reaction with the formation of a-ketoglutarate and NH4+
what is used in the excretion of amino acids
NAD+ or NADP+, which are reduced to NADH and NADPH
