Lecture 8-AMINOACIDMETABOLISMPART1 Flashcards
What is the precursor of one carbon units, , choline, cysteine ?
Serine
Glycine and serine can both produce what?
one carbon units
What is the precursor of tyrosine?
Phenylalanine
what is the precursor or Catecholamines, thyroid hormones, melanin?
Tyrosine
What is the precursor of serotonin, melatonin, NAD (P)?
Tryptophan
What is the the precursor of urea, creating, NO, Ornithine?
Arginine
What is the precursor of cysteine SAM
Methionine
What is the precursor of histamine
histidine
what is the precursor of GABA
glutamate
Explain the one carbon transfer traction of glycine and serine
What are cofactors of one carbon transfers reactions?
Biotin, S-adenosylmethionine and tetrahydrofloic acid (H4 folate)
What is special of biotin?
Usually is covalently attached to enzyme via amide to epsilon amine of lysine
CARRIER OF CO2
What are the three components of Pteroylglutamic acid (folic acid)
6-methylpterin, p-aminobenzoate, glutamate
What was the two places that 6-methylpterin carry carbon?
5,10
What enzyme reduces the two bonds in the 6-methylpterin on the pyrazine ring? what else Is needed?
Reduction by dihydrofolate reductase
NADPH+H+
What is generated when reducing the 6-methylpterin?
Tetrahydrofolic acid
What do we do to get tetrahydrofolic acid?
Reduce 6-methylpterin in pteroylglytamic acid with dihydrofolate reductase
What does dihydrofolate reductase reduce?
6-methylpterin
Carbon 5,6,7,8
What are the 3 states of tetrahydrofolate
Most reduced, intermediate and most oxidized
What molecule is the most reduced state of tetrahydrofolate ?
Methyl
What molecule is the intermediate state of tetrahydrofolate
methylene
what molecule is the most oxidized state of tetrahydrofolate
formyl, formimino, methenyl
One carbon units carrier by _________ are __________
tetrahydrofolate are interconvertible
How many times is folate reduced to get tetrahydrofolate and with what enzyme ?
twice and dihydrofolate reductase
What is giving to cancer patients?
Methrotrexate which is an inhibitor of dihydrofolate reductase
what is Methrotrexate
is a cancer drug that is an inhibitor of dihyrdofolate reductase
What is the enzyme used in for the glycine and serine metabolism ?
Serine hydroxymethyl transferase
What is the cofactor for glycine and serine metabolism
PLP
What are the reactants of glycine and serine metabolism?
serine and tetrahydrofolate
What are the products of glycine and serine metabolism
glycine and 5,10-methyenetetrahydrofolate–> Note: intermediate state
What reaction is irreversible in methyl cycle?
The second reduction of tetrahydrofolate so methylene to methyl
What is the solution of the irreversible reaction to methyl ?
B12 comes in and take the methyl group and become B12
What is the irreversible reaction to methyl and B12 called?
tetrahydrofolate trap
What happens to methyl B12?
Homocysteine takes the methyl group off B13 to make methionine with the enzyme methionine synthase
What is the enzyme used to convert homocysteine to methionine
methadone synthase
list the sources of one carbon units
serine
glycine
histidine
formaldehyde
formate
What is the enzyme used to get Co2 and NH4 from glycine?
glycine synthase –> glycine cleavage enzyme
what type of reaction is glycine to CO2 +NH4+
oxidation
What is the enzyme used for methyl B12 to homocysteine then methionine
methionine synthase
When methionine and ATP are added together produce what? which one replenishes the methyl cycle?
S-adenosylmethionine (SAM), S-Adenosyhomcysteine and homocysteine
Homocysteine replenishes
What is the precursor of cysteine
homocysteine
what are the two sources into a-ketobutyrate?
Threonine and homocysteine
what are the two sources of propionyl -CoA
valine and isoleucine
What enzymes need B12?
methionine synthase and methylmalonyl coA mutase
What is the precursor of succinyl CoA
methylmalonyl CoA
What is the enzyme used to take methylmalonyl CoA to succinyl CoA
Mehtylmalonyl CoA mutase
What enzyme is used to take methionine to homocysteine with ATP
methyltransferase
What is the precursor of homocysteine
S-Adenosylhomocysteine which comes from S-adenosylmethionine
what is important about choline?
Choline is the precursor of betaine
Explain the reaction choline to betaine and what is important of betaine?
Choline is oxidized twice to make betaine
Betamine gives one carbon unit to homocysteine to continue to make methionine
Betaine acts as?
One carbon unit transferer
what is the enzyme is used to reduce methylene FH4 to N5 methyl FH4
N5,510 methylene FH4 reductase
What enzyme would be missing if we need to use the betaine pathway?
N5,510 methylene FH4 reductase
In vitamin B12 molecule what is the center molecule with the side chains around it?
Cobalt
What is another name of Vitamin B12
cobalamin
What are the molecules that can attach to the cobalt with a ligand ?
Coenzyme B12 (5-deoxyadenosylcobalamin)
Cyanocobalamin
Methylcobalamin
T/F: we do not make B12 naturally
True
with B12 deficiency what does the RBC look like?
Macro-ovalocytes (large egg-shaped
What does b12 deficiency causes and symptoms?
Pernicious anemia
progressive loss of energy.
numbness and tingling in his toes and feet
a loss of balance on several occasions, most noticeably when walking in the dark.
a sore tongue, which made it difficult to eat.
What is an important protein in the stomach to take up B12
Intrinsic factors from parietal cells
When moved to blood what is bound to b12
TCII
TCII can also be called?
Transcobalamins
Why is B12 important
it is a cofactor enzyme to carry one carbon units
