Supplemental Readings and References
49
moc Group;
T y
n
!
«1
O
c i - c - / V -
/I S ' C
—
O - C - l H N - C — C - O '
+
H1
' —
' -------'
Insoluble Polystyrene Resin
Fmoc Protected Amino Acid
I mex I —
N
—
C
--C
—O—C
® r „ ;
piperidine in DMr
Fmoc+pipcndinc+t ()>
- H
- s O
- O
M
jN
I F moc I — N — C
C —
0
1
---------
1
H
H
Q -n=c=n-Q
C
's
DCC
REPETITIVE
CYCLK
c=o
Dicvclohcxyurea
R
2
o
R1
0
I rm o c|-N — C ---- C — N - C -----C — o — C—
—(
)
'
---------
1
h
m
h
Hj \=/
VL
3
/
I. Deprotcction of amino terminus
2. Cleavage of linkage between
polypeptide and resin by Ilr or I FA
polypeptide
+
F-gi- 0 - 0
FIGURE 3-15
Schematic representation of 9-fluorenylmethoxycarbonyl (Fmoc) solidphase polypeptide synthesis. (1) Amino-acid
containing Fmoc as N“ -amino protecting group is attached to the insoluble polystyrene resin. (2). The Fmoc protecting
group is removed by piperidine in a N,N-dimethylformamide (DMF) solution. (3). N“-amino group of amino acid
attacks dicyclohexylcardodiimide (DCC)-activated carboxyl group of amino acid 2 to form a peptide bond. (4).
Deprotection of N“-amino group of the newly integrated amino acid by piperidine in the DMF solution the synthesized
polypeptide is ultimately released from likage to the resin by treatment with hydrogen fluoride (HF) or trifluoroacetic
acid (TFA). Steps (2) and (3) are repeated until the specific polypeptide chain is synthesized.
Since the Fmoc procedure uses a base for protection
of the N-amino group, acid-labile compounds are used
to protect the side chains. Side chain protecting com-
pounds generally use a t-butyl moiety such as t-butyl
ethers for Ser, Thr, and Tyr; t-butyl esters for Asp and
Glu; and the t-BOC group for His and Lys, respectively.
Also, the trityl group is used to protect Cys, Asn, and
Gin;
the 4-methoxy
2,3,6,-trimethylbenzenesulphonyl
or
the
2,2,5,7,8,-pentamethylChroman-6-sulfonyl
groups have been used to protect the Arg guanidino
group.
Supplemental Readings and References
P. Alewood, D. Alewood, L. Miranda, et ah: Rapid in situ neutralization
protocols for t-Boc and Fmoc solid-phase chemistries.
M ethods in Enzy-
m ology
289,
14 (1997).
J. A. Borgia and G. B. Fields: Chemical synthesis of proteins.
Trends in
Biotechnology
18,
243 (2000).
