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Updated: Jun 27, 2026

T-wave Ion Mobility-mass Spectrometry: Basic Experimental Procedures for Protein Complex Analysis
Published on: July 31, 2010
Relationship between beta4 hydrogen bond and beta6 hydrophobic interactions during aggregate, fiber or crystal
Kazuhiko Adachi1, Min Ding, Toshio Asakura
1Division of Hematology, The Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA. adachi@email.chop.edu
Abstract:
Oversaturated deoxy-alpha(2)beta(2)(T4V) aggregated instantly without a delay time, which is in contrast to the delay time before the generation of fibers of deoxy-HbS and deoxy-alpha(2)beta(2)(E6V,D73H). Solubility of deoxy-alpha(2)beta(2)(T4V) was approximately 10-fold lower than that of deoxy-HbS and was similar to oxy- and deoxy-alpha(2)beta(2)(E6V,T4V). These results indicate that beta4Val in HbA in the oxy and deoxy forms with or without beta6Val facilitates hydrophobic interaction of the A-helix with the EF helix of adjacent molecules without forming a beta4/beta73 hydrogen bond. Deoxy-HbA generated crystals following aggregation as does HbC-Harlem(alpha(2)beta(2)(E6V,D73N)), while alpha(2)beta(2)(T4V) and alpha(2)beta(2)(D73H) as well as HbS, alpha(2)beta(2)(E6V,D73H) and alpha(2)beta(2)(E6V,T4V) in the oxy and deoxy forms did not form crystals, indicating in addition to the strength of beta6 amino acid hydrophobicity that the synergism between the beta4Thr hydrogen bond and beta6 hydrophobic interaction free energies on the A-helix play a critical role in formation of fibers versus crystalline nuclei during phase transition.
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