Ligand binding properties of the sarcoplasmic reticulum (Ca2+ + Mg2+)-ATPase labelled with N-cyclohexyl-N'-(4-dimethylamino-alpha-naphthyl)carbodiimide

Biochim Biophys Acta. 1984 Jan 25;769(2):291-6. doi: 10.1016/0005-2736(84)90309-2.

Abstract

The (Ca2+ + Mg2+)-ATPase of rabbit sarcoplasmic reticulum, when labelled at two Ca2+-protected sites with N-cyclohexyl-N'-(4-dimethylamino-alpha-naphthyl)carbodiimide (NCD-4) retains Ca2+ binding capacity at the sites with Kd values of approx. 3 microM and 0.12 mM as assessed by fluorescence titration. The sites correspond to the two high-affinity Ca2+ binding sites present in the native ATPase. The NCD-4 labelled ATPase exhibits slow conformational changes at each site on addition of Ca2+. It retains the ability to form phosphoenzyme, and can most likely translocate Ca2+.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Ca(2+) Mg(2+)-ATPase
  • Calcium / metabolism
  • Calcium-Transporting ATPases / metabolism*
  • Carbodiimides / metabolism*
  • Fluorescent Dyes / metabolism*
  • Kinetics
  • Protein Conformation
  • Rabbits
  • Sarcoplasmic Reticulum / enzymology*

Substances

  • Carbodiimides
  • Fluorescent Dyes
  • Adenosine Triphosphate
  • N-cyclohexyl-N'-(4-dimethylamino-alpha-naphthyl)carbodiimide
  • Ca(2+) Mg(2+)-ATPase
  • Calcium-Transporting ATPases
  • Calcium