The pentapeptide Ac-HAAAH-NH<
SUB>2, cyclized through it
s imidazole
s by Pd
II to give [Pd(en)(peptide)]
2+, ha
s recently been evaluated by 2-D NMR and
simulated annealing a
s a
single
![](/image<font color=)
s/gifchar
s/alpha.gif" BORDER=0>-helix conformation in
solution. In the pre
sent work, we have que
stioned thi
s a
ssumption by developing Pd
2+ parameter
s for AMBER*, performing an exten
sive conformational
search for the [Pd(en)(peptide)]
2+, and deconvoluting the averaged NMR data into eight rapidly equilibrating conformation
s with population
s ranging from 2 to 55%. None of the latter corre
spond to the
![](/image<font color=)
s/gifchar
s/alpha.gif" BORDER=0>-helix, although a 3% form po
sse
sse
s a related
structure. A
s a critical component of interpreting an averaged NMR
spectrum in term
s of a
single conformation, we advi
se te
sting thi
s a
ssumption with a method that permit
s conformational deconvolution.