title: Synthesis and characterization of a peptide segment of (Ca2+ + Mg2+)-ATPase. A candidate for calcium transport site.
abstract: The second tryptic digestion (TD2) of the (Ca2+ + Mg2+)-ATPase results in the decrease of Ca2+ transport due to uncoupling and the alteration of one of the two high affinity sites to a low affinity site. The eight amino acids adjacent to the tryptic digestion site form a torus with two carboxylic side chains of one aspartic and one glutamic acid for the fast twitch skeletal ATPase and two aspartic acids for the slow twitch/cardiac ATPase toward the inside. The eight amino acid peptides were synthesized for both forms of the ATPase and their binding characteristics were studied with luminescent Eu3+ as a Ca2+ analogue. The data indicate that the peptide binds Eu3+ with 1.0 Eu3+/peptide and strips off two water molecules. The peptide region is a candidate for the Ca2+ transport site of the (Ca2+ + Mg2+)-ATPase.
mesh_terms: D000818:Animals; D001665:Binding Sites; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D005063:Europium / Q000378:metabolism; D007700:Kinetics; D009132:Muscles / Q000201:enzymology; D010446:Peptide Fragments / Q000138:chemical synthesis* / Q000378:metabolism; D011485:Protein Binding; D012519:Sarcoplasmic Reticulum / Q000201:enzymology; D013050:Spectrometry, Fluorescence; D014357:Trypsin
chemical_list: D010446:Peptide Fragments; D005063:Europium; D014357:Trypsin; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases