THE STRUCTURE OF SILURUS-ASOTUS (CATFISH) ROE LECTIN (SAL) - IDENTIFICATION OF A NONCOVALENT TRIMER BY MASS-SPECTROMETRY AND ANALYTICAL ULTRACENTRIFUGATION

We identified a noncovalent trimer of Sirurus asotus roe lectin (SAL) at Mr 95,362 along with its monomer at M-r 31,750 by electrospray ioni zation mass spectrometry when SAL was dissolved in 0.5% acetic acid, s prayed into the ion source with methanol as a sheath Liquid, and desol vated at 75 degrees C in a heated capillary column. The molecular weig ht of SAL, determined by the sedimentation equilibrium method, was 95, 200 and the sedimentation coefficient (S-20,S-w) Of SAL in water was 5 .58. SAL existed as a noncovalent trimer in solution and showed the ab ility to agglutinate rabbit erythrocytes. SAL showed three peaks (sal 1, sal 2, and sal 3) by C-8 reverse-phase HPLC, and these appeared to be a monomer, a dimer, and a trimer, respectively, by matrix-assisted laser desorption ionization-tine of flight mass spectrometry. sal 1 an d sal 2 were shown to have a structure interchangeable with that of sa l 3 in water. (C) 1997 Academic Press.