Changes in Bovine Myoglobin Due to Interaction with Methyl Linoleate in a Model System

Authors

  • Z. NAKHOST,

    1. Authors Nakhost and Karel are affiliated with the Dept. of Nutrition & Food Science, Massachusetts Institute of Technology, Cambridge, MA 02139.
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  • M. KAREL

    1. Authors Nakhost and Karel are affiliated with the Dept. of Nutrition & Food Science, Massachusetts Institute of Technology, Cambridge, MA 02139.
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  • Presented at the 42nd Annual Meeting of the Institute of Food Technologists, Las Vegas, NV, June 22–25, 1982.

  • This work was supported in part by contract #DAAK 60–81-C-0091 from the Natick Research & Development Laboratories. Dr. I.A. Taub was the Project Officer and the authors are grateful for his criticism, advice and evaluation.

  • Opinions expressed in this paper are those of the authors, and do not necessarily reflect those of the Natick Research & Development Laboratories.

ABSTRACT

Changes in myoglobin due to lipid oxidation were studied in a model system, consisting of a mixture of metmyoglobin and methyl linoleate (2:1), which was mechanically emulsified, freeze-dried and stored at 37°C. After storage, samples were reconstituted, centrifuged and lipid fractions were separated and tested for degree of oxidation. The protein was recovered in two fractions: “soluble fraction” (supernatant) and “aggregates” (precipitated proteins). Absorption spectroscopy confirmed protein insolubilization due to formation of aggregates. SDS-PAGE of metmyoglobin recovered from both fractions indicates gradual formation of covalently bound polymers upon storage. Isoelectric focusing (IEF) shows formation of new bands and zones with a drastic acidic shift of isoelectric points. Two-dimensional IEF/SDS-PAGE shows that the newly formed bands on IEF correspond to covalently bound myoglobin polymers.

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