LECTURE 27 - NITROGEN METABOLISM Flashcards
what are some N containing compounds that are made from AAs?
what is nitrogen fixation and how do plants do it?
fixation: take N2 gas and make it into NH3
plants have a symbiotic relationship with diazotroph bacteria which express nitrogenase that fix atmospheric nitrogen
nitrogenase requires energy to break the stable N2 bond
industrial nitrogen fixation:
the haber bosch reaction that uses a nitrogen fixing catalyst
what is assimilation?
incorporation of ammonia to amino acids
plants take the NH3 and put it on glutamine with glutamine synthetase
inc
what are some nitrogen assimilation reactions
how are dietary proteins digested?
how are dietary amino acids imported and what is the exception?
what are the three categories of amino acids?
nonessential: we can make them
alanine
asparagine
aspartate
glutamate
serine
essential: we cannot make them, must ingest them
histidine
isoleucine
leucine
lysine
methionine
phenylalanine
threonine
tryptophan
valine
conditionally essential: we can make them from essential amino acids, depend on the consumption of essentials
arginine
cysteine (from methionine)
glutamine
glycine
proline
tyrosine (from phenylalanine)
what is the amino acid pool used for?
energy production
synthesis of glucose or FAs
synthesis of non protein molecules that contain N (heme, purine, creatine, neurotransmitters)
what is the stereochemistry of amino acids?
they are all L amino acids
what are principles of the amino acid pool
what can the NH3 generated during AA breakdown do to us?
what are some assimilation reactions
what are the most abundant amino acids in the plasma?
alanine and glutamine
characteristics of glutamine and its regulation
glutamine is the biggest reservoir of NH3 in the body
used for protein synthesis
non toxic storage of NH4
regulated by glutamine synthetase (organs) and glutaminase (liver)
NH3 generates urea which is excreted by urine, urine is degraded by bacteria which regenerates N2
