Milestones in the techniques and methodology of polypeptide structure
determination include the determination of the sequence of insulin by
Sanger in 1951 (I) and the introduction of the repeti- tive degradation
of proteins with phenylisothiocyanate by Edman in 1959 (2). The
automation of Edman chemistry (3) played a major role in the
determination of polypeptide structures. Important modifications of
Edman chemistry include the solid-phase approach by Laursen in 1971 (4)
and the use of modified Edman reagents such as 4-N,
N-dimethylaminoazobenzene-4'-isothiocy- ate (DABITC) for manual
sequencing by Chang et al. (5) in 1976. A second major breakthrough in
the analysis of polypeptides was automated amino acid analysis described
by Spackman et al. in 1958 (6). However, during the period from 1975 to
1980, it became increasingly clear that the amount of material required
for struc- tural analysis was more than could be easily isolated for the
vast majority of proteins. The field was criticized for its lack of
sensitive techniques for the analysis of growth factors, immune
modulators, membrane receptors, and peptide hormones. In addition, very
little had been done to modernize and improve the original instruments
introduced in the mid-1960s. The first indications of improved
instrumentation for Edman chemistry came from Wittmann-Liebold's
laboratory (7), followed by the introduction of a "micro" sequencer by
Hunkapiller and Hood in 1978 (8). The movement toward improved
instrumentation culminated in the "gas"-phase sequencer of Hewick et al.
(9) in 1981.
