Complete amino acid sequence of the sarcoplasmic calcium‐binding protein (SCP‐I) from crayfish (Astacus leptodactilus)

Abstract
The complete amino acid sequence of the alpha chain of the dimeric sarcoplasmic Ca2+‐binding protein (SCP‐I=α2) from crayfish (Astacus leptodactylus) has been determined by partial automatic sequencing of the peptides derived from tryptic digests of the protein after citraconylation or treatment with 1,2‐cyclohexanedione. Overlapping peptides were obtained by cleavage with o‐iodosobenzoic acid, or digestion with Staphylococcus aureus protease, thermolysin and pepsin. The acetylated N‐terminus was identified by fast atom bombardment mass spectrometry. The monomeric protein contains 192 amino acids and has an M r of 21 643. The sequence shows the presence of three calcium‐binding sites and perhaps of two others that may be degenerated.