Hemoglobin (Hb) is an important component in red blood cells of the vertebrate. It is a major respiratory protein with oxygen or carbon dioxide transport function. Hb has been reported to contain bioactive peptides which have antibacterial and antioxidant activities. In this study, the alpha-chain hemoglobin(alpha Hb) gene of Crocodylus siamensis was cloned into the three different expression vectors and expressed in Escherichia coli BL21 (DE3). The recombinant aHb proteins from all constructs could be expressed and purified. The result from UV-visible absorption spectra showed a similar pattern of all recombinant proteins to the oxy-hemoglobin form of intact Hb. The different recombinant alpha Hb could exhibit antioxidant activities. All recombinant proteins could inhibit the growth of Bacillus spp. Especially, most of the recombinant proteins could inhibit the growth of Bacillus amyloliquefaciens TISTR 1045 better than intact one. The result obtained from this study can provide us further information about the possibility using of alpha Hb as a supplementary food. (C) 2015 Elsevier Inc. All rights reserved.