  Infrared emission features toward interstellar gas of the IC 348 star cluster
in Perseus have been recently proposed to originate from the amino acid
tryptophan. The assignment was based on laboratory infrared spectra of
tryptophan pressed into pellets, a method which is known to cause large
frequency shifts compared to the gas phase. We assess the validity of the
assignment based on the original Spitzer data as well as new data from JWST. In
addition, we report new spectra of tryptophan condensed in para-hydrogen
matrices to compare with the observed spectra. The JWST MIRI data do not show
evidence for tryptophan, despite deeper integration toward IC 348. In addition,
we show that several of the lines attributed to tryptophan are likely due to
instrumental artifacts. This, combined with the new laboratory data, allows us
to conclude that there is no compelling evidence for the tryptophan assignment.
