Site-directed mutagenesis in hemoglobin. Effect of some mutations at protein interfaces

B. Vallone, P. Vecchini, V. Cavalli, M. Brunori

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

The role of selected amino acid residues in the monomer-monomer contacts of Hb A has been studied by site-directed mutagenesis of the α chain bearing substitutions in the subunit surfaces. Mutation α 38Thr → Trp induced a stabilization of tetrameric Hb-CO with a decrease of the Kd for the equilibrium α2β2 ⇌ 2αβ, but had no effect on ligand binding. Mutation α40Thr→Arg resulted in a complete loss of cooperativity in ligand binding. Mutation α103His→Val had no noticeable effect. We also studied the behaviour of isolated, mutated α chains with respect to self association: compared to wt α chains, mutant α38Thr→Trp showed stabilization of the dimeric state and (at high protein concentration) a detectable amount of tetramers. Mutant α103His→Val showed only a minor stabilization of the α2 dimer.

Original languageEnglish
Pages (from-to)117-122
Number of pages6
JournalFEBS Letters
Volume324
Issue number2
DOIs
StatePublished - Jun 14 1993

Keywords

  • Hemoglobin mutant
  • Protein engineering
  • Subunit contact

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