Oxidation and chemical modification of lung β-galactosidase-specific lectin

P. L. Whitney, J. T. Powell, G. L. Sanford

Research output: Contribution to journalArticle

68 Scopus citations

Abstract

Galaptins are small, soluble, lectins with a specificity for β-galactose residues. Many galaptins are inactivated by atmospheric oxygen and are protected by disulphide-reducing reagents. We find that each subunit of rat lung galaptin contains one residue of tryptophan and six of cysteine. Oxygen inactivates rat lung galaptin by oxidation of the cysteine residues. During oxidation, the normal dimeric structure is maintained and all disulphide bonds are formed within individual subunits. Exogenous thiols protect against inactivation, but oxidized thiols accelerate inactivation. Human lung fibroblast galaptin is almost completely inactivated within 1 h in tissue culture medium at 37 ° C. Alkylation of native rat lung galaptin with iodoacetate or ethyleneimine causes substantial loss of activity. The dimeric galaptin structure is maintained. In contrast, alkylation with iodoacetamide yields carboxamidomethyl-galaptin, which is fully active and stable to atmospheric oxygen in the absence of disulphide-reducing reagents. This derivative is very useful for studies of galaptin properties and function.

Original languageEnglish (US)
Pages (from-to)683-689
Number of pages7
JournalBiochemical Journal
Volume238
Issue number3
DOIs
StatePublished - Jan 1 1986

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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