Meeting Abstract
5.10 Thursday, Jan. 3 Parvalbumin’s ability to bind calcium in the face of varying environmental salinity in the Atlantic stingray, Dasyatis sabina HEFFRON, Jennifer K.*; MOERLAND, Timothy S.; Florida State University; Florida State University heffron@bio.fsu.edu
The Atlantic stingray, Dasyatis sabina, is a euryhaline species that migrates back and forth between freshwater and the marine environment. However, there is one population that has taken up permanent residence in a freshwater environment, the St. Johns River System, Fl. Past research has focused mainly on plasma osmolality, but less is known about the effects of urea, betaine, and TMAO on the function of intracellular proteins of this organism. This research examined the intracellular side of the puzzle by investigating the response of an important muscle protein, parvalbumin (PV) to the denaturing effects these organic osmolytes have been shown to have on other proteins. D. sabina exhibited two isoforms of PV. Dissociation constants (KD) were determined in the presence and absence of betaine, urea, and TMAO. In the 2:1 ratio of urea:methylamines, KD was determined to be 6.03+0.05nm for Isoform I and 11.09+0.50nm for Isoform II. When tested in the presence of each osmolyte independently Isoform I showed no significant difference in its ability to bind calcium with the exception of betaine (8.23+0.05nm). Isoform II, on the other hand, was determined to be enhanced in its ability to bind calcium in the presence of each osmolyte separately (~5.10 nm). This protein could provide insight into how other proteins found in muscle function in the presence of urea, betaine or TMAO independently and in the well known 2:1 ratios of urea:methylamines (betaine and TMAO) found in elasmobranchs.
