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.