The Acidic Molten Globule State of α-Lactalbumin Probed by Sound Velocity

Bengt Nölting, Min Jiang, Stephen G. Sligar

Research output: Contribution to journalArticlepeer-review


We have investigated the structure and the chemical and conformational relaxation in the acidic molten globule state of α-lactalbumin (A-state) by using ultrasonic velocimetry. The A-state of the α-lactalbumin at pH 2 exhibits an 11% lower sound-velocity increment than that of the native state at neutral pH and 2-MHz sound frequency. An excess of calcium decreases this effect. For lysozyme, the difference in sound velocity between pH 7 and 2 is significantly smaller. Lysozyme has a large sequence homology and structure similarity to the native α-lactalbumin, but no molten globule state in aqueous solution has been described. The destabilized apo-state of α-lactalbumin at neutral pH exhibits a small decrease of roughly 4% in its sound-velocity increment relative to the native state. The large sound-velocity decrease of the A-state relative to that of the native state of α-lactalbumin indicates significant conformational relaxation at a time scale faster than 500 ns in the acidic molten globule at pH 2.

Original languageEnglish (US)
Pages (from-to)9879-9882
Number of pages4
JournalJournal of the American Chemical Society
Issue number22
StatePublished - Nov 1 1993

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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