Calcium activated neutral proteinase (CANP II) from bovine CNS myelin was isolated and purified by my collaborator, Dr. Banik. This enzyme was used to digest human myelin basic protein, component 1 (HBP-1) because the sequence of this protein is known. CANP digests were separated on HPLC into pooled fractions. N- and C-terminal sequences of these pools yielded eleven cleavage sties in HBP-1. The major site was Val(94)-Thr(95). Dr. Banik has also isolated and purified multicatalytic proteinase complex (MPC) from bovine brain. MPC also digests HBP-1 but at a much slower rate. Human myelin basic protein (HBP) occurs in multiple forms. Three of these isoforms have been highly purified - HBP-1 (unmodified BP), 17.2kDa HBP (missing residues 106-116) and HBP 3pT98 (phosphorylated on Thr(98)). When compared with circular dichroism (CD) studies done on HBP-1, the CD studies of 17.2kDa HBP showed about 9% increase in ordered structure and those of HBP 3pT98 about a 12% increase. Both modifications of HBP-1, the delection of residues 106-116 and the addition of a single phosphate promoted secondary structure, probably an increase of beta-structure.
