Identification of a labelled peptide after stoicheiometric reaction of fluorescein isothiocyanate with the Ca2+ -dependent adenosine triphosphatase of sarcoplasmic reticulum.
Incorporation of 4.5 nmol fluorescein isothiocyanate/mg rabbit sarcoplasmic reticulum, or of 7.4 nmol/mg purified ATPase, was sufficient to inhibit the activity completely. These results are not consistent with the suggestion (Pick, U. and Karlish, S.J.D. (1980) Biochim. Biophys. Acta 626, 255-261) that 2 mol ATPase were inhibited by each mole of reagent incorporated. A single labelled peptide was purified from the inhibited ATPase and it was shown that Lys 3/190, 10 residues from the N-terminus of tryptic fragment B, was the reactive lysine residue. This site is close to a potential nucleotide-binding fold in the ATPase sequence. A similar peptide showing only 2 conservative replacements was isolated from the sarcoplasmic reticulum of the lobster.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001665:Binding Sites; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D055598:Chemical Phenomena; D002621:Chemistry; D016650:Fluorescein-5-isothiocyanate; D005452:Fluoresceins / Q000494:pharmacology; D009132:Muscles / Q000201:enzymology; D008121:Nephropidae; D010455:Peptides / Q000032:analysis*; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D013861:Thiocyanates / Q000494:pharmacology
D000596:Amino Acids; D005452:Fluoresceins; D010455:Peptides; D013861:Thiocyanates; D000252:Calcium-Transporting ATPases; D016650:Fluorescein-5-isothiocyanate