Combinatorial peptide on-resin analysis: optimization of static nanoelectrospray ionization technique for sequence determination

The optimizations of static nanoelectrospray parameters to determine peptid e or mimetic sequences released from resin were explored. Several different manufacturers of probe tips were utilized and a method was developed for t he direct analysis of bead-bound peptides by nanoelectrospray. The method i nvolved minimum sample handling to assure maximum recovery from individual beads. Parameters that were explored included an inside and outside wash of the probe Zip, the distance from the probe housing to the probe tip, sourc e temperature, drying gas flow, individual tips and presence of beads. The same soluble synthetic peptide was used in all comparisons, which had a mol ecular weight of 717 amu. The discovery of the sequence of a bead-bound pep tide was achieved. The parameters that were found to effect signal were out side wash, presence of bead and distance. There was the need for pneumatic assist to initiate electrospray on some occasions, although this generally resulted in unsatisfactory performance.