aa oxidation and urea cycle

nitrogen cycle

nitrogen needs to be fixed before it can be used

used for fuel

AA are ____ when not needed for new protein synthesis or during starvation when carbs are unavailable

carbon skeletons and nitrogens

aa catabolism works to resolve what 2 metabolic issues

amine groups

never want free ____ in cells or body

amino acids

amine groups are transported as ____ from organs to liver where they are used to synthesize urea then be excreted

glutamine (glutamate) and alanine

what aa are transported/delivered for deamination in the liver

aminotransferases

key enzymes in moving amino groups between different carbon skeletons

pyridoxal phosphate

cofactor for aminotransferases

liver

urea cycle occurs where?

glutamine

transports ammonia in the blood

2 nitrogens

how many excess nitrogen are brought per molecule of a-ketoglutarate

alanine

specifically in muscle how do we transport amino groups to the liver

alanine

3C molecule so lose less carbon by transporting this from muscle vs glutamine

Glucogenic

AA that end up as TCA intermediates that can contribute carbons to synthesis of glucose

ketogenic

AA that end up as ketone bodies

lysine and leucine

ketogenic only AA

glutamate

it is possible to deaminate AA from diet directly in liver to make ___

carbamoyl phosphate + alanine

synthesis of what signals entry into the urea cycle

a-ketoglutarate/glutamate

alanine/pyruvate

OAA/aspartate

pairs for a-keto acid stuff

urea cycle nitrogen

2 from urea, 1 carbamoyl phosphate, 1 from aspartate

ornithine

need ___ to continue the urea cycle

OAA and fumarate

how is the urea cycle linked to the TCA

mitochondria and cytosol

where does the urea cycle occur

ornithine and citrulline

2 nonprotein AA in the urea cycle

2 compartments

full urea cycle takes place in ____

atp and ppi hydrolysis

what drives the urea cycle forward

arginosuccinate

____ is a connection between the urea cycle and the TCA

fumarate

arginosuccinate --> (TCA)

arginine

argunosuccinate --> (urea cycle)

aspartate

OAA is transaminate to what in the mitochondria because it is needed for a second nitrogen in the urea cycle

transcriptional regulation

____ of genes for the urea cycle enzymes

carbamoyl phosphate synthase 1

regulation of ____ by n-acetylglutamate is one way to regulate the urea cycle

positively regulates acetyl coA and glutamate

arginine ______ in the urea cycle (regulation)