Question

pans (a)-(?). Use a separate answer book provided for this question. (a) Give a mechanism for the reaction involving the convers generate enzyme-linked \(\beta\)-ketothioester D. CO\(_2\)H SCoA of acetyl-CoA and malonyl-CoA C to (8) HO C OSCoA + EnzS SEnz steps C D E (b) Including all intermediate structures, propose the sequence of reactions that are involved in the multi-step conversion of D, with several \"inputs\" of C, into enzyme-linked, thioester E (mechanisms not required). (12) (c) Subsequent reaction with C converts E into F which then undergoes formation of zearalenone. Suggest a mechanism for the conversion of F into zearalenone. C E EnzS steps Zearalenone (15) (d) Illustrate how analysis of the structure, in terms of starter and extender units can provide a rationalisation of the biosynthetic origin of the macrolide erythronollde A (shown below). (9) (e) Identify all oxygens in the structure which originate from the original polyketide chain and a position in which deoxygenation has occurred. (6) OH OH "OH "OH Erythronolide A

          pans (a)-(?).
Use a separate answer book provided for this question.
(a)
Give a mechanism for the reaction involving the convers
generate enzyme-linked \(\beta\)-ketothioester D.
CO\(_2\)H
SCoA
of acetyl-CoA and malonyl-CoA C to
(8)
HO
C
OSCoA
+
EnzS
SEnz
steps
C
D
E
(b) Including all intermediate structures, propose the sequence of reactions that are involved in the
multi-step conversion of D, with several \"inputs\" of C, into enzyme-linked, thioester E (mechanisms
not required).
(12)
(c) Subsequent reaction with C converts E into F which then undergoes formation of zearalenone.
Suggest a mechanism for the conversion of F into zearalenone.
C
E
EnzS
steps
Zearalenone
(15)
(d) Illustrate how analysis of the structure, in terms of starter and extender units can provide a
rationalisation of the biosynthetic origin of the macrolide erythronollde A (shown below). (9)
(e) Identify all oxygens in the structure which originate from the original polyketide chain and a
position in which deoxygenation has occurred.
(6)
OH
OH
"OH
"OH
Erythronolide A

pans (a)-(?).
Use a separate answer book provided for this question.
(a)
Give a mechanism for the reaction involving the convers
generate enzyme-linked β-ketothioester D.
CO2H
SCoA
of acetyl-CoA and malonyl-CoA C to
(8)
HO
C
OSCoA
+
EnzS
SEnz
steps
C
D
E
(b) Including all intermediate structures, propose the sequence of reactions that are involved in the
multi-step conversion of D, with several ïnputsöf C, into enzyme-linked, thioester E (mechanisms
not required).
(12)
(c) Subsequent reaction with C converts E into F which then undergoes formation of zearalenone.
Suggest a mechanism for the conversion of F into zearalenone.
C
E
EnzS
steps
Zearalenone
(15)
(d) Illustrate how analysis of the structure, in terms of starter and extender units can provide a
rationalisation of the biosynthetic origin of the macrolide erythronollde A (shown below). (9)
(e) Identify all oxygens in the structure which originate from the original polyketide chain and a
position in which deoxygenation has occurred.
(6)
OH
OH
"OH
"OH
Erythronolide A

Added by Purificaci-N C.

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