Covalent labeling strategies for the improvement of whole protein and large peptide sequence determination by electron transfer dissociation

摘要

Large, covalent labels capable of carrying mobile protons were used to derivatize intact apomyoglobin (17 kDa). Targeted groups near the N-and C-terminus were efficiently labeled and directed ETD fragmentation to areas previously lacking coverage. Carboxylic acids were esterified to prevent salt-bridge formation and, as a result, charge state distribution increased and additional fragment ions were observed. Novel Aspect-An LTQ-Orbitrap modified with front-end ETD/IIPT enables multiple-fills and, combined with covalent modifications that enhance ETD, yields 93% sequence coverage of intact apomyoglobin.