cell wall synthesis

Question 1

step 1 in cell wall synthesis

Answer 1

synthesis of N-acetyl-muramic acid

requires phosphoenolpyruvate

Question 2

step 2 in cell wall synthesis

Answer 2

sequentially adding of L-ala, D-glu and L-lys

done by specific enzyme

Question 3

what is special about D-glu

Answer 3

linked by Gamma link via its side chain carbon

Question 4

step 3 in cell wall synthesis

Answer 4

synthesis of D-ala-D-ala

Question 5

what enzymes are used to synthesis D-ala-D-ala

Answer 5

racemase and

synthase

Question 6

step 5 in cell wall synthesis

Answer 6

transfer of C-55 lipid

Question 7

step 7 in cell wall synthesis

Answer 7

addition of 5 glycines to (epsilon)-amino of lysine

Question 8

step 8 in cell wall synthesis

Answer 8

transfer of the disaccharides unit to the existing cell wall releasing C-55-p-p

Question 9

step 9 in cell wall synthesis

Answer 9

recycling of C-55-p-p

Question 10

step 10 in cell wall synthesis

Answer 10

cross-linking of the linear chains with release of 1 D-ala

Question 11

which steps are inhibited

Answer 11

step 1
step 4
step 8
step 9 and 
step 10

Question 12

step 1 what is inhibiting it

Answer 12

blocked by phosphomycin

Question 13

phosphomycin what does it do

Answer 13

similar to PEP competitive inhibitor

Question 14

step 4 what inhibits it

Answer 14

cycloserine

Question 15

cycloserine

Answer 15

its a competitive inhibitor

binds more tightly then natural compound

Question 16

step 8 what inhibits it

Answer 16

vancomycin and

risocetin

Question 17

vancomycin

Answer 17

binds to D-ala-D-ala end
preventing enzyme substrate complex
gram +ve MRSA affective
not absorbed in the gut so used in gastrointestinal infection
good for patients allergic to penicillin

Question 18

step 9 what inhibits it

Answer 18

blocked by Bacitracin

Question 19

step 10 what inhibits it

Answer 19

penicillin (G)
stops cross linking from side chain glu and D-ala
its a Beta lactam which occupies the active site of the enzyme
covalent thus irreversible
inhibits transpeptidation enzyme

Question 20

step 6 in cell wall synthesis

Answer 20

addition of N-acetyl-glucosamine