CHEMICAL CROSS-LINKING WITH DISUCCINIMIDYL TARTRATE DEFINES THE RELATIVE POSITIONS OF THE 2 ANTIPARALLEL COILED COILS OF THE DESMIN PROTOFILAMENT UNIT

Filaments formed by desmin, the myogenic intermediate filament protein , were crosslinked with the lysine specific crosslinker DST (disuccini midyl tartrate; 0.64 nm span) and three DST crosslinked peptides were characterized. Two correspond to crosslinks previously obtained with t he longer crosslinker EGS (ethylene glycol bis(succinimidylsuccinate), 1.61 nm span) which defined the antiparallel on-stagger relationship of neighbouring coiled coils. The two DST crosslinks now provide the r elative positions of the coiled coils within a limit of about 9 alpha- helical residues. The third DST crosslink most likely connecting two h elices of a single coiled coil gives a direct measure of the distance spanned in DST crosslinks.