Microsequence analysis: III. Automatic solid‐phase sequencing using dabitc

The automation of solid-phase sequencing, using the Edman-type degradation [ 11, was originally perfected by Laursen and co-workers [2,3]. Several books have been devoted to this subject [4,5]. The original idea was to provide a means for degrading insolubilized peptides and thus prevent the well-known ‘washout’ problem common to the liquid-phase instruments. Alternatively various groups have attempted to render the peptide or protein more polar (thus reducing its solubility in organic solvents) but only through the recent use of polybrene [6,7] has liquid-phase sequencing for most peptides at low concentrations (<50 nmol) become possible. In solid-phase technology on the other hand, emphasis has been directed toward improving coupling yields and providing the means to couple peptides arising from a variety of specific cleavages. Prior to the introduction of DABITC [8] there had been little interest in developing substitutes for PITC which would simplify detection and increase sensitivity. In manual liquid[9,10] and solid-phase