title: Halistaurin, phialidin and modified forms of aequorin as Ca2+ indicator in biological systems.
abstract: Two kinds of aequorin-type photoproteins, i.e., halistaurin and phialidin, and four kinds of modified forms of aequorin, i.e., products of acetylation, ethoxycarbonylation, fluorescamine-modification and fluorescein labelling, were prepared. The modified forms of aequorin were more sensitive to Ca2+ than was aequorin in their Ca2+-triggered luminescence reactions, whereas halistaurin and phialidin were less sensitive. The emission maxima of luminescence were all within a wavelength range 450-464 nm, except for fluorescein-labelled aequorin, which emitted yellowish light (lambda max. 520 nm). A new technique of measuring Ca2+ concentration is suggested.
mesh_terms: D000331:Aequorin / Q000031:analogs & derivatives; D002118:Calcium / Q000378:metabolism*; D008164:Luminescent Proteins; D013053:Spectrophotometry
chemical_list: D008164:Luminescent Proteins; C046164:halistaurin; C046165:phialidin; D000331:Aequorin; D002118:Calcium