Comparison of two calcium-dependent proteinases from bovine heart

Dorothy E. Croall, George N. DeMartino

Research output: Contribution to journalArticlepeer-review

51 Scopus citations


We have purified two calcium-dependent proteinases from bovine heart. Each enzyme was a heterodimer. One proteinase (designated CDP-I) contained subunits of 84 and 26 kDa. The other proteinase (designated CDP-II) contained subunits of 80 and 26 kDa. The large subunit of each proteinases accounted for the calciuim-dependent proteolytic activity of the respective enzyme and could be isolated from the small subunit by caseim-Sepharose affinity chromatography. The large subunits of CDP-I and CDP-II appeared to be distinctly different proteins, based on differences in peptide maps and on the lack of detectable immunologic cross-reactivity. On the other hand, the small subunits of the proteinase appeared to be identical peptides, based on peptide mapping and on two-dimensional gel electrophoresis. The function of the small subunit is unknown. The two calcium-dependent proteinases share many catalytic properties, including the nature of proteinase activity against several myofibrillar proteins. However, the proteinases were distinguished by different calcium-concentration requirements. CDP-II required 300 mgM Ca2+ for half-maximal activity and 750 mgM Ca2+ for full activity. CDP-I required only 30 mgM Ca2+ for half-maximal activity and 100 mgM for full activity.

Original languageEnglish (US)
Pages (from-to)348-355
Number of pages8
JournalBiochimica et Biophysica Acta (BBA)/Protein Structure and Molecular
Issue number3
StatePublished - Aug 14 1984


  • (Bovine heart)
  • Ca dependence
  • Protein degradation
  • Proteinase

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology


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