Ca2+ induces conformational changes and unfolding of threadfin bream myosin and actin, which is enhanced at higher temperatures.
Ca2+-induced myofibrillar changes warrant caution in calcium-treated food processing; leaves open relevance to mammalian cardiac muscle.
The effect of Ca 2+ on physicochemical and conformational changes of threadfin bream (TB) myosin and actin during setting at 25 and 40°C was investigated. Ca 2+ ion at 10 to 100 mM induced the unfolding of myosin and actin as evident by an increase of surface hydrophobicity (S o ANS) at 40 °C. Total SH groups also decreased with an increased Ca 2+ concentration, suggesting that Ca 2+ promoted the formation of disulfide bonds during setting at 40 °C. Both hydrophobic interactions and disulfide linkages were involved in formation of myosin aggregates at 40 °C and were enhanced by addition of 10 to 100 mM Ca 2+ . Myosin Ca‐ATPase activity decreased when Ca 2+ was greater than 50 mM, indicating conformational changes of myosin head. Circular dichroism spectra demonstrated that Ca 2+ reduced the α‐helical content of myosin and actin incubated at either 25 or 40 °C. Ca 2+ induced conformational changes of TB myosin and actin incubated at 40 °C to a greater extent than at 25 °C.
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Hemung et al. (2005) studied this question.
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