biosynthesis of nonessential and specialized AAs

Question 1

what is a key urea cycle intermediate?

Answer 1

arginine

Question 2

___________ dilates blood vessels, raising blood supply and lowering blood pressure. ______ helps protect tissues from damage due to low blood supply

Answer 2

nitric oxide

Question 3

what structure do I need to know concerning the synthesis of creatine and creatinine?

Answer 3

creatine kinase and creatine

Question 4

creatinine

Answer 4

break-down product of creatine-P in our muscles; produced at a fairly constant uncatalyzed rate; amount depends on muscle mass, high in men; clearance rate tells us how well kidney is working

Question 5

glutamate transamination

Answer 5

a-KG +AAx <-transaminase<> glutamate + a-KAx

Question 6

glutamate reductive amination

Answer 6

a-KG + NH3 + NADPH<-Glutamate dehydrogenase<> Glutamate + NADP+

Question 7

glutamate hydrolysis

Answer 7

Glutamine + H2O <- Glutaminase<> Glutamate + :NH3

Question 8

what is made exclusively by glutamine synthetase (cytosolic enzyme)?

Answer 8

Glutamine

Question 9

what do futile cycles do and how do we prevent them from occurring?

Answer 9

they pointlessly hydrolyze ATP; cells keep opposing enzymes in separate compartments

Question 10

transamination aspartate

Answer 10

OAA + Glutamate <- Transaminase<> Aspartate + a-KG

Question 11

Aspartate Hydrolysis

Answer 11

Asparagine + H2O<-asparaginase<> aspartate + :NH3

Question 12

Aspartate + Gln + ATP<> asparagine + Glu AMP

Answer 12

one site hydrolyzes Gln to generate nascent :NH3; :NH3 travels through aprotic tunnel; other site has already made B-Aspartyl-AMP intermediate; :NH3 attacks B-aspartyl-AMP to make asparagine + AMP

Question 13

ALanine formation (formed solely from transamination)

Answer 13

pyruvate + glutamate <> alanine + a-KG

Question 14

what is a key step in proline biosynthesis

Answer 14

reduction of glutamate to glutamate semi-aldehyde

Question 15

glutamate semi-aldehyde also undergoes transamination to form _________

Answer 15

ornithine

Question 16

what is a precursor for arginine synthesis within the urea cycle?

Answer 16

glutamate

Question 17

increasing ornithine will increase …

Answer 17

urea cycle output

Question 18

conversion to hydroxyproline within collagen

Answer 18

prolyl hydroxylase is easily deactivated, forming bound Fe(III)-O^- , which must be reduced by vitamin C to restore enzyme

Question 19

tyrosine, a conditionally essential AA

Answer 19

plays important roles in protein structure, serves as phosphoryl- and sulfuryl-group acceptor in key regulatory enzymes and fibrin (clotting protein)

Question 20

Phenylketonuria

Answer 20

very high serum phenylalanine, high urinary phenylpyruvate (formed by transamination)

Question 21

autosomal recessive

Answer 21

two copies of abnormal gene must be present for the disease or trait to develop

Question 22

molecular basis of PKU

Answer 22

blood phenylalanine rises to 20x normal level, elevated phenylalanine damages nerve function

Question 23

PKU is a treatable disease…

Answer 23

Requires diet that is extremely low in phenylalanine.
Diet must be strictly followed
Requires full “buy-in” by parents and pediatric patient.
Should maintain “low-phenylalanine” diet into adulthood to ensure
better physical & mental health
Becomes a balancing act, when a PKU woman becomes pregnant

Question 24

cysteine

Answer 24

conditionally essential amino acid

Question 25

S-adenosyl-methionine aka SAM or Ado-Met

Answer 25

methylating agent for around 300 metabolites & most abundant methionine containing metabolite

Question 26

what are two structures concerning cysteine do you need to know?

Answer 26

cysthathionine, homocysteine, and S-adenosyl-homocysteine