One or More Serum Factors Promote Peptide Utilization in Cultured Animal Cells

Manuscript received 19 August 1996. Initial reviews completed 21 October 1996. Revision accepted 9 December 1997.

Yuanlong Pan, Patrick K. Bender^*, R. Michael Akers, and Kenneth E. Webb Jr.

Departments of Animal and Poultry Sciences, ^* Biochemistry and Anaerobic Microbiology and  Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0306

We have shown previously that MACT-T and C₂C₁₂ cells utilize methionine-containing di- to octapeptides as methionine sources for protein accretion and cell proliferation in the presence of 60 mL/L desalted fetal bovine serum. In this study, serum factors that may regulate the use of peptides as amino acid sources in C₂C₁₂ and MAC-T cells were examined. The basal media contained methionine-free Dulbecco's modified Eagle's medium supplemented with 4.0 mL/L bovine serum lipids, 10 mL/L chemically defined lipid concentrate, bovine insulin (1 mg/L), 30 mL/L low protein serum replacement (LPSR-1) or 60 mL/L desalted animal serum. Treatment media included basal media supplemented with no methionine, L-methionine, or one of the methionine-containing peptides. L-Methionine promoted protein and DNA accretion (P < 0.05) in the presence of desalted animal sera, insulin or LPSR-1. Methionine-containing peptides also promoted protein and DNA accretion (P < 0.05) in the presence of desalted animal sera or LPSR-1, but not with insulin, except methionylleucine. In a cell-free medium, fetal bovine serum hydrolyzed peptides to varying degrees. We conclude that animal sera contain one or more factors that regulate utilization of peptides as amino acid sources for C₂C₁₂ and MAC-T cells.

The Journal of Nutrition Vol. 128 No. 4 April 1998, pp. 744-750
Copyright ©1998 by the American Society for Nutritional Sciences