Isolation, characterization and nucleotide sequence of the muscle isoforms of creatine kinase from the Antarctic teleost Chaenocephalus aceratus

Paul Winnard, Robert E. Cashon, Bruce D. Sidell, Michael E. Vayda

Research output: Contribution to journalArticlepeer-review

Abstract

Creatine kinase (CK) was isolated from the white muscle of the Antarctic icefish Chaenocephalus aceratus, which is deficient in glycolytic capacity. C. aceratus white myotomal creatine kinase (MMCK) displayed an apparent Km at 0.5°C of 0.06 mM for ADP and 17 mM for Phosphocreatine. These Km values are similar to those reported for other vertebrate MMCKs at their physiologically relevant body temperatures. C. aceratus MMCK exhibited optimal activity at pH of 7.6-7.7 at 0.5°C, in contrast to rabbit MMCK which had optimum activity at pH 6.2 at 30°C. The apparent Vmax of C. aceratus MMCK at 0.5°C is 94±4 S.D. (n=9) μmol ATP/min/mg (i.e. U/mg), which is comparable to rabbit MMCK assayed at 20°C and 8-fold greater than rabbit MMCK measured at 0.5°C. DEAE chromatography of C. aceratus white muscle CK resolved two distinct activity peaks. Cloning and sequencing of C. aceratus CK cDNAs confirmed that two muscle-specific isoforms of CK were expressed that were distinct from the mitochondrial and brain isoforms. Icefish MMCK was sensitive to transient temperature elevation, and the DEAE-fractionated forms were highly unstable. These results indicate that C. aceratus MMCK displays significant activity at physiological temperature and intracellular pH of icefish muscle that could contribute to sustaining energy charge during burst-swimming.

Original languageEnglish (US)
Pages (from-to)651-667
Number of pages17
JournalComparative Biochemistry and Physiology - B Biochemistry and Molecular Biology
Volume134
Issue number4
DOIs
StatePublished - Apr 1 2003
Externally publishedYes

Keywords

  • Antarctic
  • Chaenocephalus aceratus
  • Channichthyidae temperature adaptation
  • Creatine kinase
  • Icefish
  • Myotomal muscle
  • Notothenidae
  • Polar
  • Teleost

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Molecular Biology

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