Expression and characterization of rainbow trout Oncorhynchus mykiss recombinant myoglobin.

Recombinant expression system was established for rainbow trout myoglobin (Mb) considering its unique primary structure of having one unusual deletion and two cysteine residues in contrast to the other fish Mbs. The obtained recombinant Mb without His-tag showed non-cooperative thermal denaturation profile. The presence of free cysteine residue(s) in rainbow trout Mb was demonstrated by reacting with a sulfhydryl agent, 4, 4´-dithiodipyridine, which ultimately resulted in the oxidation of Mb with characteristic changes in visible absorption spectra. Besides, the recombinant Mb displayed steady peroxidase reactivity indicating in vivo roles of Mb as a reactive oxygen species scavenger. The findings of the present study indicate that the solitary rainbow trout Mb, which ultimately manifest typical secondary structure pattern and corroborate characteristic functionality, can be over expressed in recombinant system devoid of fusion tag.