The molecular size of Myxicola infundibulum chlorocruorin and its subunits

Serge N. Vinogradov, Paul R. Standley, Mark G. Mainwaring, Oscar H. Kapp, Albert V. Crewe

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

The molecular shape and size of the extracellular chlorocruorin of Myxicola infundibulum was determined using scanning transmission electron microscopy and its dissociation in the presence of sodium dodecyl sulfate (SDS) was investigated using polyacrylamide gel electrophoresis. The shape of the chlorocruorin is that of a two-tiered hexagon with a vertex-to-vertex diameter of 29.0-29.5 nm and a height of 19.0-19.7 nm: it appears to be smaller by 5-10% relative to several annelid extracellular hemoglobins examined by scanning transmission electron microscopy. The quarternary structure of the chlorocruorin appears to be sensitive to ca(II) concentration; dissociation fragments of the whole molecule were observed, consisting of octamers and dimers of one-twelfth subunits. The unreduced chlorocruorin dissociated into two subunits with estimated molecular masses of 23000 (1) and 60000 (2); the reduced chlorocruorin dissociated into subunits with estimated molecular masses of 13000 (I), 14000 (II) and 30000 (III). SDS-polyacrylamide gel electrophoresis of reduced subunits 1 and 2 showed that subunit 1 corresponded to subunit III and that subunit 2 dissociated to subunits I and II. Densitometry of the polyacrylamide gels indicates that 85-90% of the Myxicola chlorocruorin consists of disulfide-bonded tetramers of polypeptide chains of about 15000. Such a pattern of subunit aggregation has not been observed previously in annelid extracellular hemoglobins and chlorocruorins.

Original languageEnglish (US)
Pages (from-to)43-50
Number of pages8
JournalBiochimica et Biophysica Acta (BBA)/Protein Structure and Molecular
Volume828
Issue number1
DOIs
StatePublished - Mar 22 1985
Externally publishedYes

Keywords

  • (M. infundibulum)
  • Chlorocruorin
  • Electron microscopy
  • Molecular shape

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology

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