Abstract:

The structural elucidation of metmyoglobin (Mb) is helpful for understanding the mechanism of meat color.
Molecular information and three-dimensional structure of metmyoglobin (pMetMb) in pig myocardium were studied by
SDS-PAGE, UV spectroscopy, amino acid analysis, mass spectrometry and bioinformatics. The peptide chain of pMetMb
was composed of at least 133 amino acids (AAs). AAs from pMetMb lacked proline (Pro) and arginine (Arg) compared
with horse Mb (hMb). pMetMb was matched 79.7% (100% confidence) with gi|494385 in NCBI database, suggesting that
the length of pMetMb peptide was in the range of 133–153 AAs including 7 α-helixes and 2 310 helixes in its secondary
structure. Due to the 310 helixes, hydrophobic groups in pMetMb had increased interaction with each other and the peptide
chain highly folded as globin subunit, while hMb contained no 310 helixes. Both His64 and His93 located at the 6th α-helix
and 7th α-helix contained imidazole group with nitrogen (N-) that could bind with Fe2+/Fe3+ to form heme-Fe domain which
was embed into hydrophobic groups, facilitating electron transfer and oxidation-reduction and consequently for maintaining
desirable meat color.

Key words: metmyoglobin (MetMb), amino acids, alpha helix, molecular and structural information, pig myocardium