[Study of the amino acid residue topography of the adenosine triphosphatase center of (Ca--Mg)-dependent sarcoplasmic reticulum adenosine triphosphatase by kinetic and spectral methods].
The topography of HS- and NH2-groups and tryptophane residues in ATPase centre of (Ca--Mg)-ATPase on sarcoplasmic reticulum (SR) was investigated by kinetics, electron spectroscopy and spectrofluorimetry method. Both o-phthalaldehyde interacting with lysine or arginine residue or with end amino acid and fluorescein dimercuric acetate interaction with cysteine residue of HS-groups make (Ca--Mg)-ATPase both in SR and the pure enzyme completely inactive at molar ratio enzyme: inhibitor equal to 1 : 1. A 500 molar ATP surplus reduces drastically the enzyme inactivation rate by both inhibitors. The data supplied by the spectrofluorimetry and the induction-resonance theory were used to calculate the distances between nearest tryptophane residues and chromophore (o-FTC) generated by o-phthalaldehyde interaction with NH2-group the protein amino acid residue (17 A) and o-FTC and fluorescein dimercuric acetate (19 A) attached to enzyme HS-group. Because o-FTC is inside the protein pocket it is not accessible to J- ions up to 2.5 M KJ. However some tryptophane resudies and fluorescein dimercuric acetate attached to HS-group are near to the macromolecule surface. Lysine (or arginine residues) or end amino acid NH2-group and cysteine residues HS-group, and some tryptophane residues are at ATPase centre of (Ca--Mg)-ATPase from sarcoplasmic reticulum. Possible topography of the centre is discussed.
D000596:Amino Acids; D001665:Binding Sites; D000252:Calcium-Transporting ATPases; D002384:Catalysis; D055598:Chemical Phenomena; D002621:Chemistry; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D011487:Protein Conformation; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D013050:Spectrometry, Fluorescence; D013057:Spectrum Analysis; D009764:o-Phthalaldehyde
D000596:Amino Acids; D009764:o-Phthalaldehyde; D000252:Calcium-Transporting ATPases; D008274:Magnesium
Issledovanie topografii aminokislotnykh ostatokov adenozintrifosfataznogo tsentra (Ca--Mg)-zavisimoĭ adenozintrifosfatazy sarkoplazmaticheskogo retikuluma kineticheskimi i spektral'nymi metodami.