amino acid biosynthesis Flashcards
how many amino acids can we produce (non-essential)
10
list the 10 non-essential amino acids
alanine, glutamate, glutamine, proline, arginine, serine, glycine, cysteine, aspartate, asparagine
list 3 ways in which amino acids are derived
glycolysis intermediates, CAC intermediates, PPP intermediates
describe how amino acids can be derived from the PPP
Glucose-6-P can be converted to metabolites by donating electrons to NADP+, producing lots of NADPH
what do aminotransferases do
move amino groups from one molecule to another
what is the name of the leftover molecule when an aminotransferase removes it’s amino group
carbon skeleton
which amino group was removed to create a carbon skeleton: backbone or R group
backbone (because not every a.a has an R group amine)
what is another name (the chemical name) for an amino acid minus its R group
a-keto acid
last class we saw that a-KG can make glutamate which can then make glutamine. List the other two derivatives of glutamate (aka a-KG derivatives)
proline and arginine
describe how proline is made from glutamate
glutamate is reduced by dehydrogenase and NADPH, The resulting molecule is spontaneously (non-enzymatically) cyclized. A final NADPH reduction = proline
to make proline: what enzyme is used
glutamate dehydrogenase
to make proline: ATP cost?
1 ATP
to make proline: NADPH cost?
uses 2 NADPH
describe how you make arginine from glutamate
reduce glutamate with NADPH. Aminotransferase introduces a second amino group, leaving glutamate as a-KG. Resulting molecule = ornithine, which enters the urea cycle to form arginine
to make arginine: enzymes used?
aminotransferase
to make arginine: ATP cost?
2 ATP
to make arginine: NADPH cost?
1 NADPH used
to make arginine: what intermediate is produced
ornithine
to make arginine: what happens to ornithine during the pathway
it enters the urea cycle to eventually form arginine
how many amino groups does arginine have
4
how many amino groups does urea have
2
what amino acid is produced from 3-phosphoglycerate? what amino acids does that produce?
serine, which makes glycine and cysteine
describe how we make serine from 3-phosphoglycerate
3-PG is oxidized by NAD+. Aminotransferase adds an amino group. Phosphatase removes the phosphate
to make serine: enzymes used?
aminotransferase and phosphatase
to make serine: ATP cost?
none
to make serine: byproducts? (ie are the electron carriers oxidized or reduced)
NAD+ is used, NADH is produced
describe how glycine is produced from serine
hydroxymethyltransferase removed OH and methyl group from serine
to make glycine: enzymes used?
hydroxymethyltransferase
to make glycine: ATP cost?
none
to make glycine: and electron carriers?
none
describe how to make cysteine from serine
plants uptake sulfates (SO4 2-) from the soil which are reduced by NADPH to sulfide (S2-). The sulfide is exchanged for the serine OH
to make cysteine: enzymes used?
none that are mentioned (S is replaced with OH)
to make cysteine: ATP cost?
none
to make cysteine: electron carriers?
NADPH used
which amino acid does OAA make
aspartate
which amino acid does aspartate make (that we can synthesize)
asparagine
which amino acid does pyruvate make (that we can synthesize)
alanine
describe how alanine is made from pyruvate
pyruvate is transaminated via aminotransferase
describe how aspartate is made from OAA
OAA is transaminated via aminotransferase
describe how asparagine is made from aspartate
aspartate is amidated. Glutamine donates the NH4+. Enzyme used = asparagine synthetase
to make asparagine: enzyme?
asparagine synthetase
to make asparagine: ATP cost?
1 ATP used
what does ALL stand for
acute lymphoblastic leukemia
ALL produces an overabundance of _____________
immature lymphocytes
what does “acute” mean in acute lymphoblastic leukemia
cancer progresses rapidly, developing within weeks and becoming possibly fatal within months
which enzyme is produced in very little amounts in the malignant lymphocytes in ALL
asparagine synthetase
synthesis of which amino is blocked during ALL? why? how do people with ALL get this amino acid?
synthesis of asparagine is blocked since very little asparagine synthetase is produced in the malignant lymphocytes. They must acquire it from the diet
treatment for ALL involves which enzyme
asparaginase
describe the actions of asparaginase enzyme in ALL treatment
the enzyme depletes asparagine in the blood serum, removing the extracellular source of it for these cancer cells = cuts off the asparagine source for the bad cells
in ALL treatment, what happens to the cancerous cells once asparaginase removes the extracellular source of asparagine
without ability to synthesize Asn and no Asn to utilize from the surrounding serum, the cells die
which amino acids are derived from PEP
the ringed amino acids: phenylalanine, tyrosine, tryptophan
T or F: PEP is the only thing that can make tyrosine
false; it can also be made from phenylalanine
before making the three ringed amino acids, what does PEP need to make?
chorismate
describe how chorismate is made from PEP
2x PEP (3C) and erythrose 4-phosphate (4C) form 10C chorismate
describe how tyrosine is made from chorismate (PEP)
a mutase swaps groups off the chorismate ring. the intermediate is then oxidized, decarboxylated, and transaminated
describe how phenylalanine is made from chorismate (PEP)
a mutase swaps groups off the chorismate ring. The intermediate is then decarboxylated and transaminated
formation of which amino acid involves oxidation: tyrosine or phenylalanine
tyrosine
what amino acid is formed from ribose-5-phosphate
histidine
what intermediate must be made from ribose-5-P before histidine formation
5-phosphoribosyl-1-pyrophosphate (PRPP)
how many phosphates does PRPP have
3
once PRPP is formed from ribose-5-P, describe how histidine is formed
histidine is formed from 5 PRPP carbons and 2 oxygens, a nitrogen and carbon from the adenine ring of ATP, a nitrogen from glutamine, and a nitrogen from glutamate
list the molecules that contribute atoms to histidine
glutamine, PRPP, glutamate, adenine
some of the byproducts from histidine synthesis can be used for ___ synthesis
purine
what type of feedback inhibition regulates amino acid synthesis pathways
allosteric feedback inhibition
why is allosteric feedback inhibition used to regulate amino acid synthesis pathways
to ensure amino acids aren’t made when they’re already in high concentrations
why can negative feedback inhibition be problematic
problematic when the same intermediate is needed for multiple amino acids, but it’s being inhibited by one product
describe how enzyme multiplicity comes into play with a.a synthesis regulation
the enzymes in a pathway will have multiple isozymes, and isozymes are inhibited by different molecules in the pathway. This way, inhibition of A1 isozyme by one product reduces overall A activity, but A2 and A3 are still active to make the other products
T or F: the effect of enzyme multiplicity inhibitors is cumulative
true
list 6 amino acid derivatives
nucleotides, heme, lignin, auxin, alkaloids, neurotransmitters
what is heme a derivative of
glycine
heme is required for proper function of both ___ and ___
hemoglobin and cytochromes
heme degrades into __ and __
Fe2+ and bilirubin
where/in what conditions will heme be degraded into Fe2+ and bilirubin
occurs in damaged/dying RBCs in the spleen
T or F: bilirubin is insoluble
true
from the spleen, where does bilirubin travel to
liver
how does bilirubin travel to the liver
bound to serum albumin
what happens to bilirubin upon arrival to the liver
converts to a water soluble bile pigment in the liver and released into the small intestine
what happens to bile pigment once it’s made from bilirubin in the liver and enters the small intestine
some of it makes its way to the kidneys and a derivative helps make urine yellow
T or F: bilirubin makes urine yellow
false; a derivative of bilirubin makes urine yellow
T or F: bilirubin makes feces brown
false; a derivative makes feces brown
describe what happens when you bruise
blood vessels in/near the skin burst and the damaged RBCs release heme
why do bruises change color
occurs as heme loses oxygen
describe what happens as bruises change from purple to yellow
heme loses oxygen = purple. Heme degrades into an intermediate biliverdin = green, and eventually bilirubin = yellow
what happens if bilirubin is in the blood (caused by excess bilirubin)
leads to jaundice
what is lignin a derivative of
phenylalanine and tyrosine
what is the role of lignin
forms secondary cell walls in plants, large component of wood and bark
what is auxin a derivative of
tryptophan
role of auxin?
regulates shoot/fruit/lead growth and helps stems bend towards light
what part of the plant secretes auxin
the tip of the plant shoot
what are flavoured molecules derivatives of
phenylalanine and tyrosine
what are alkaloids derivatives of
phenylalanine and tyrosoine
what are alkaloids
nitrogenous chemicals formed in plants
list 4 alkaloids
caffeine, capsaicin, morphine, nicotine
what are neurotransmitters derivatives of
tyrosine, glutamate, tryptophan, histidine
_____ is a key step in most pathways to synthesize NTs
decarboxylation
list 5 NTs
epinephrine, norepinephrine, histamine, serotonin, GABA
