N-Ac-Ser-Asn-Lys-Phe-Leu-Gly-Thr- Trp-Lys-Leu-Val-Ser-Ser-Glu-Asn-Phe-Asp-Asp-Tyr- Met-Lys-Ala-Leu-Gly-Val-Gly-Leu-Ala-Thr-Arg-Lys- Leu-Gly-Asn-Leu-Ala-Lys-Pro-Asn-Val-Ile-Ile-Ser- Lys-Lys-Gly-Asp-Ile-Ile-Thr-Ile-Arg-Thr-Glu-Ser-Gly-

The reaction of the P2 protein from rabbit sciatic nerve with CNBr produced four peptides: a 20-residue peptide (CN3) containing tryptophan which occupies the blocked NHZ terminus; Peptide CN1, a large peptide comprising over 70% of the P2 molecule; Peptide CN2, a fraction containing two tightly bound peptides having 2 half-cystine residues and comprising the COOH terminus; and Peptide CN4, a nonapeptide of the CN3 region obtained by abnormal CNBr cleavages of the bonds between Trp-8 and Lys-9 and Asp-17 and Asp18, respectively. The complete sequence of Peptide CN3 was determined by sequenator and dansyl-monitored Edman procedures; the NHz-terminal sequence was shown to be N-Ac-Ser-Asn-Lys. Peptide CN3 is joined to Peptide CN1 by a Met-Lys linkage; an overlap peptide obtained by BNPS-skatole cleavage of the P2 protein between “ p 8 and Lys-9 proved invaluable in linking Peptides CN3 abd CN1. We determined 44 and 33 residues, respectively, for Peptide CN1 and the BNPS-skatole peptide with a sequenator. These studies may bear on our understanding of allergic neuritis and Guillain-Barre syndrome since the P2 protein is an antigenic target in these diseases. Peptides CN1, CN2, and CN3 add up to 138 amino acids and account for the total P2 protein; the sequence of the first 64 residues of the P2 protein is: N-Ac-Ser-Asn-Lys-Phe-Leu-Gly-ThrTrp-Lys-Leu-Val-Ser-Ser-Glu-Asn-Phe-Asp-Asp-TyrMet-Lys-Ala-Leu-Gly-Val-Gly-Leu-Ala-Thr-Arg-LysLeu-Gly-Asn-Leu-Ala-Lys-Pro-Asn-Val-Ile-Ile-SerLys-Lys-Gly-Asp-Ile-Ile-Thr-Ile-Arg-Thr-Glu-Ser-GlyPhe-Lys-Asn-Thr-Glu-Ile-Thr-Phe.