WALLACE, R.S. *; MOERLAND, T. S.; Florida State University; Florida State University: The effect of varying temperature on calcium binding of parvalbumin in Fundulus heteroclitus
The mummichog, Fundulus heteroclitus, is an abundant fish of the East Coast in saltwater marshes and tidal creeks. Over the course of one tidal cycle, Northern populations of this species may be exposed to wide temperature fluctuations. Parvalbumin (PV) is a calcium binding protein that assists in the relaxation phase of muscle contraction. PV was purified by AMS fractionation and subsequent separation through gel permeation and DEAE chromatography. Protein purity was verified with SDS-PAGE and Western blots. PV dissociation constants (KD) were determined for F. heteroclitus from Woods Hole, Mass. at four temperatures ranging from 0-25�C. Temperature sensitivity of PV function was determined by measuring the dissociation constants with a fluorescent indicator assay that uses the fluorescent calcium indicator fluo-3 in competition with PV. KD values obtained for F. heteroclitus were 7.88 nM, 7.77 nM, 7.64 nM, and 8.25 nM at 0, 5, 15, and 25�C, respectively. Thus, calcium binding by PV from F. heteroclitus is essentially independent of temperature, a pattern that is markedly different than that of PV from other teleost species found in temperate and polar regions. These findings suggest parvalbumin in F. heteroclitus has adapted to function over wide fluctuations in temperature. Supported by NSF IBN-98-08120 and DARPA N66001-02-C-8030
