Complete Amino Acid Sequence of Globin Chains and Biological Activity of Fragmented Crocodile Hemoglobin (Crocodylus siamensis)

Hemoglobin, alpha-chain, beta-chain and fragmented hemoglobin of Crocodylus siamensis demonstrated both antibacterial and antioxidant activities. Antibacterial and antioxidant properties of the hemoglobin did not depend on the heme structure but could result from the compositions of amino acid residues and structures present in their primary structure. Furthermore, thirteen purified active peptides were obtained by RP-HPLC analyses, corresponding to fragments in the alpha-globin chain and the beta-globin chain which are mostly located at the N-terminal and C-terminal parts. These active peptides operate on the bacterial cell membrane. The globin chains of Crocodylus siamensis showed similar amino acids to the sequences of Crocodylus niloticus. The novel amino acid substitutions of alpha-chain and beta-chain are not associated with the heme binding site or the bicarbonate ion binding site, but could be important through their interactions with membranes of bacteria.