Adipyl crosslinked bovine hemoglobins as new models of allosteric systems

Herman E. Kwansa, Alice De Young, Daniele Arosio, Anna Razynska, Enrico Bucci

Research output: Contribution to journalArticle

Abstract

As indicated by peptide analyses and mass spectrometry estimations, intramolecular crosslink with bis(3,5-dibromosalicyl)adipate of bovine hemoglobin results in the formation of two main components covalently bridged across the β-cleft. In one component the crosslink joins the β1V1-β2K81 residues (XL-Peak-1), in the other the bridge is between the β1K81-β2K81 residues (XL-Peak-2). Both components are tetrameric with a mass near MW = 67 kDa as estimated by gel filtration, and a hydrodynamic radius near 3.20 nm, estimated by dynamic light scattering. They have very low oxygen affinity with Pm near100 mmHg (XL-Peak-1) and near 70 mmHg (XL-Peak-2) respectively at 37°C, at neutral pH. The Bohr effect is almost absent in XL-Peak-1, while in XL-Peak-2 it is very near normal. Both systems show oxygen binding cooperativity with an index near n = 2.0. Flash photolysis kinetics of the recombination with CO could be resolved into a fast and a slow component. The amplitude of the fast rates were not concentration-dependent. The stopped- flow kinetics were autoaccelerating, consistent with their ligand-binding cooperativity. All rates were very similar to those of normal hemoglobin, suggesting that the oxy- rather than the deoxy-forms of the systems were affected by the crosslink. (C) 2000 Wiley-Liss, Inc.

Original languageEnglish (US)
Pages (from-to)166-169
Number of pages4
JournalProteins: Structure, Function and Genetics
Volume39
Issue number2
DOIs
StatePublished - May 1 2000

Keywords

  • Bovine hemoglobin
  • CN-B fragments
  • Crosslinked hemoglobins
  • Low affinity hemoglobins
  • Peptide maps

ASJC Scopus subject areas

  • Structural Biology
  • Biochemistry
  • Molecular Biology

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