非常详细的综述性文章
116
药学学报Acta
PharmaceuticaSinica
2007,42(2):111—117
yields
fortherapidSPPS.using
Boc—aminoacid
derivatives,of
CGRP(human一Ⅱ.caleitonin
gene—
relatedpeptide)(8—37).They
observed
that
coupling
yields
are
highly
dependent
on
thesolventused.Maximumresinsolvationoccurred
with
NMP.
NMP—DMSO(8:2)andDMSO.Inefficientsolvationof
the
peptide—resin
occurred
with
these
solvents
and
resultedinpoorsyntheseswithaveragecouplingyieldsof78.1。88.9and
91.8%.respectively.Superior
peptide—resin
solvationwas
obtainedusing
DMA
(dimethylacetamide)
and
DMF,
resultingin
significantlyhigheraveragecouplingyieldsof98.0and
2).
2
Average
couplingyieldsforthe
synthesisof
Solventsystem
Avg.coupling
yield/%
DMF
provided
themosteffective
peptide—resinand
was
theonly
solventfrom
whichCGRP
obtained
as
a
singlemajorproductinthe
cleavedmaterial.Itshouldpointout
thatunderconditions
the
peptidyl—resin
has
differentresponses
even
inthe
same
solvent.
solventnot
onlywiththechangeofchainlengthbutalso
withthe
alternation
of
stages
ineach
syntheticcircle.such
as
the
deprotecting
and
couplingsolvents,isnecessary
for
the
enhancement
of
coupling
Thus,the
success
of
SPPSisoften
dependent
solvationoftheresinandthegrowingresin—bound
chain.Theuse
ofnewsupports
thatincreaseseparation
and
peptide
chain
solvation
is
CLPSER(cross—linked
polystyrene—
acrylate
resin)。3“showed
excellent
in
a
broadrangeofsolventsused
in
SPPS.newresinwascomparedwithcommercialsupportsas
MerrifieldandSheppardresinsbysynthesizing
acylcarrier
protein(65—74)fragment
underthe
experimental
conditions.HPLC
(high—
liquid
chromatography)profiles
revealed
highefficiencyofthenewlydevelopedsupport.CM
3
(polyethylene
glyc01)一based
resin,performing
excellentlyfor
the
preparationofhydrophobic,highly
structured,andpoly—Argpeptides,ascomparedtoPS
(polystyrene)resins.Themechanistic
reason
behind
thesynthetic
efficiencyofthe
new
resinwasfoundto
beitsabilitytoinducerandomcoilconformation
to
the
growing
peptidechains.
Conclusions
The
phenomenon
of“difficultsequences’’hasbeenattributedto
the
self—association
of
the
peptide
chainbyformationofhydrogenbonds
andresultin
an
incompletecouplingreaction.Itissequencedependentup
to
nowno“GoldenRule”existswhich
allows
predictionofaggregationduringthesynthesisof
a
sequence!The
aggregation
has
a
tendency
tooccur
a
sequence
richinhydrophobicresidues;ithasbeen
as
at
the5/6th
residuefromtheC—terrainus
not
occurring
after
the
21st
one.Two
main
can
beused
to
disrupttheaggregation:the
one
consistsin
modifyingtheenvironmentinwhich
synthesisismadeand
to
introduceelementsknown
disrupthydrogenbonds,
which
include
the
thesolventssuch
as
DMF,DMSO,
mixedsolvent;additionofchaotropicsalts:
at
elevated
temperature.Theotherapproach
to
introducebackboneprotecting
groups
or
spacer
which
willprevent
the
formationof
hydrogen
sHch
as,using
more
potent
newsupportswithexcellentswelling,
reasonableschemes
for
fragment
the
microwave—assistedSPPS
33,34一
alsodescribed
as
successfulstrategiesforsynthesis
sequences”.
[1]Tickler
AK,Barrow
CJ.wadeJD.hnprovedpreparation
of
amyloid-betapeptides
S
as
Nalpha—Fmoc
deprotection
reagent[J]
唱&
吐
队%
2001,7:488一
494.
DalPozzoA,NiM,MuziL,eta1.Aminoacidbromides:theirN—protectionand
use
in
the
synthesisof
pepti(1eswith
extremely
difficult
sequences[J].J
Org
Chem,
2002,67:6372—6375.Ball
HL,King
DS,CohenFE,eta1.Engineering
the
prionproteinusingchemicalsynthesis[J].J
Pept
Res,
2001,58:357—374.
Miranda
LP,AlewoodPF.
Challengesfo。protein
chemicalsynthesisinthe21st
century:bridginggenomics
and
proteomics[J].J
PeptSci,2000,55:217—226.
99.5%,respectively(TableandTablethenew
CGRP(8—37)
in
describedbut
approachesfirst
theto
following:changingsolvationNMP,orcoupling
is
(8—37)wascrudedifierentswelling
unitsbonds.Approaches
Therefore,varyingpeptidedifferentchanging
very
reagents,usingdesigning
condensations,andare
of“difficult
RefeFences
efficient.
upon
peptideinterchainpreferred.
ethyleneglycolswellingThesuch
an
same
performance
the