Neural calcium-activated neutral proteinase inhibitors

An antibody specifically immunoreactive with an immunogen, wherein said immunogen consists essentially of a substantially purified, low molecular weight calpastatin with a molecular weight of about 60 kilodaltons, as determined by gel filtration, and consisting of a dimer of about 31 kilodalton subunits, as determined by SDS PAGE under reducing conditions, and wherein said calpastatin has a pI range of 4.2-4.7 on an isoelectric focusing gel and an N-terminal amino acid sequence as follows:

• NH.sub.2 -X-Glu-Lys-Glu-Thr-Lys-Glu-Glu-Gly-Lys-Pro-Lys-Gln-Gln-Gln-X-X-Lys-Glu-Lys (SEQ ID NO:
• 2)
• wherein X represents an unknown amino acid residue;
• wherein said calpastatin has the following amino acid composition:
• ______________________________________ Mole % ______________________________________ Asx 8.4 Thr 3.6 Ser 10.3 Glx 17.1 Pro 5 Gly 16.4 Ala 6.4 Cys/2 0 Val 4.3 Met 0.9 Ile 3.3 Leu 3.1 Tyr 2.7 Phe 7 Lys 1.3 His 4 ______________________________________
• wherein:
• Asx=sum of aspartic acid (D) and asparagine (N), and
• Glx=sum of glutamic acid (E) and glutamine (Q);
• and wherein said calpastatin is capable of inhibiting calcium-activated neutral proteinase activity.