Structural Changes in Cod Myosin after Modification with Formaldehyde or Frozen Storage

Authors

  • M. CARECHE,

    1. Author M. Careche is with the Instituto del Frío (C.S.I.C.) Ciudad Universitaria s/n, E-28040, Madrid, Spain. Author Li-Chan is with the Dept. Of Food Science, Univ. Of British Columbia, 6650 NW Marine Drive, Vancouver, BC, Canada V6T 1Z4. Address inquiries to Dr. E.C.Y. Li-Chan.
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  • E.C.Y. LI-CHAN

    1. Author M. Careche is with the Instituto del Frío (C.S.I.C.) Ciudad Universitaria s/n, E-28040, Madrid, Spain. Author Li-Chan is with the Dept. Of Food Science, Univ. Of British Columbia, 6650 NW Marine Drive, Vancouver, BC, Canada V6T 1Z4. Address inquiries to Dr. E.C.Y. Li-Chan.
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  • Thanks are due to Ms. Angela Kummer for skillful technical assistance. This work has been financed by a NATO Collaborative Research Grants Programme Ref. CRG 940695, by Spanish ALI 94-0954-C02-01-02 and by research grants from the Natural Sciences and Engineering Research Council of Canada.

ABSTRACT

Structural changes in cod myosin after formaldehyde (FA) addition with and without subsequent freezing at – 18°C were examined by Raman spectroscopy, ANS hydrophobicity, solubility and SDS-PAGE profiles. Protein solubility decreased by >90%, whereas ANS fluorescence showed little change, possibly due to a balance between soluble and insoluble fractions differing in exposed hydrophobicity. SDS-PAGE showed irreversible insolubilization at increasing FA concentration, especially after frozen storage. Raman spectral analysis indicated a change in secondary structure of aquacide concentrated myosin preparations, from 95%α-helix in the control (no FA) to 60% after 12 mM FA treatment. Changes in vibrational modes assigned to aliphatic residues suggested involvement of hydrophobic interactions after FA addition or frozen storage.

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