Methionine/cysteine Metabolism

Question 1

Why is SAM (S-adenosyl methionine important?)

Answer 1

for 1-carbon transfer. It will methylate a histone

Question 2

where does SAM come from?

Answer 2

Methionine

Question 3

homocysteine reacts with

Answer 3

serine

Question 4

when homocysteine and serine reacts they form _____ usine

Answer 4

cystathionine / cystathionine synthase

Question 5

what cofactor does cystathionine synthase use?

Answer 5

B6/PLP/pyridoxine

Question 6

how does cystathionine enter the TCA cycle?

Answer 6

It undergoes a transulfation, and then breaks down into propionyl coA–> malonyl coA –> succinyl coA

Question 7

deficiency in cystathionine synthase causes

Answer 7

homocysteneuria

Question 8

when you hear cardiovascular disease think

Answer 8

homocysteneuria

Question 9

can have homocysteneuria 2 ways

Answer 9

1) cystathionine synthase defect or the lack of B12 so you have no remethylation pathway of homoscsteine to methionine

Question 10

betaine

Answer 10

methyl group donor and can stimulate the formation of methionine from homocysteine

Question 11

cofactor of BCAAD

Answer 11

thiamine

Question 12

disease when you have a defect in BCAAD

Answer 12

Maple syrup urine disease

Question 13

lysine and leucine

Answer 13

are solely ketogenic –> cannot be glucogenic

Question 14

how is proprionyl coA converted to methyl malonyl coA

Answer 14

propionyl coA carboxylase

Question 15

what is the cofactor used with proprionyl coA carboxylase

Answer 15

biotin

Question 16

how do you treat MSUD

Answer 16

thiamine

Question 17

which enzymes in the branch chain pathway can form glucogenic intermediates

Answer 17

valine and isoleucine

Question 18

increaed proprionic acid in proprionic aciduria inhibits

Answer 18

NAG synthase, so you dont get N-acetyl glamate, whcih activates CPS1. It also inhibits Glycine cleavage complex

Question 19

multiple carboxylase deficiency

Answer 19

reduced biotin will effect every carboxylase

Question 20

what two things will increase in proprionic acidemia

Answer 20

glycine and NH3

Question 21

how do you treat proprionic acemida?

Answer 21

you will decresae VOMIT and give biotine. You can also use carnitine to saok up an acetly coA, or you can treat with antibiotivs

Question 22

what do you use carnitine for

Answer 22

carnitine reacts with acetyl coA, and will soak up proprionyl coA and help w proprionyl acidemia

Question 23

carboxylases use

Answer 23

biotin

Question 24

dehydrogenases use

Answer 24

thiamine