Peptide-bound methionine as methionine sources for protein accretion and cell proliferation in primary cultures of ovine skeletal muscle.

Ruminants have high concentrations of peptide-bound amino acids in the circulation. Earlier studies in our laboratory showed that a myogenic cell line (C2C12) developed from mouse skeletal muscle and a mammary epithelial cell line (MAC-T) developed from bovine mammary epithelial tissues are able to utilize peptides as amino acid sources. In this study, primary cultures of ovine myogenic satellite cells were evaluated for their ability to use peptide-bound methionine as a source of methionine for protein accretion and cell proliferation. The basal medium contained methionine-free Dulbecco's modified Eagle's medium supplemented with 6% desalted fetal bovine serum. Treatment media included the basal medium supplemented with no methionine, methionine or one of 22 methionine-containing peptides. No protein or DNA accretion was observed in the presence of basal medium alone. Growth responses to all of the peptides were obtained, with protein and DNA accretion ranging from 49 to 107% and from 45 to 144% of the corresponding methionine response, respectively. These results indicate that the ovine myogenic satellite cells possess the ability to utilize methionine-containing peptides as methionine sources for protein accretion and cell proliferation.