CALCIUM-BINDING PROPERTIES AND SEQUENCE OF FROG (RANA-TEGRINKA) PARVALBUMIN AS DETERMINED BY ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY

The primary structure and calcium-binding properties of frog parvalbum in (R. tegrinka, alpha linkage) was determined by using electrospray i onization-mass spectrometry and Edman degradation, A portion of the pr otein molecules are N-terminally blocked and the blocking group was de termined to be an acetyl group by tandem mass spectrometry. The protei n contains two cysteines, with one conserved at position 34 and the ot her located at the C-terminus (residue 110), The protein also dimerize s via a Cys-Cys linkage and binds to one Ca2+ with high affinity, An a dditional Ca2+ ion is bound only at high calcium concentration levels, The calcium-binding characteristics for frog parvalbumin are differen t from those found for rabbit and rat parvalbumins, which bind to two Ca2+ ions in a cooperative manner.