Title
Reversible denaturation of Brazil nut 2S albumin (Ber e1) and implication of structural destabilization on digestion by pepsin
Author
Koppelman, S.J.
Nieuwenhuizen, W.F.
Gaspari, M.
Knippels, L.M.J.
Penninks, A.H.
Knol, E.F.
Hefle, S.L.
de Jongh, H.H.J.
TNO Kwaliteit van Leven
Publication year
2005
Abstract
The high resistance of Brazil nut 2S albumin, previously identified as an allergen, against proteolysis by pepsin was examined in this work. Although the denaturation temperature of this protein exceeds the 110 °C at neutral pH, at low pH a fully reversible thermal denaturation was observed at ∼82 °C. The poor digestibility of the protein by pepsin illustrates the tight globular packing. Chemical processing (i.e., subsequent reduction and alkylation of the protein) was used to destabilize the globular fold. Far-UV circular dichroism and infrared spectroscopy showed that the reduced and alkylated form had lost its β-structures, whereas the α-helix content was conserved. The free energy of stabilization of the globular fold of the processed protein as assessed by a guanidine titration study was only 30-40% of that of the native form. Size exclusion chromatography indicated that the heavy chain lost its globular character once separated from the native 2S albumin. The consequences of these changes in structural stability for degradation by pepsin were analyzed using gel electrophoresis and mass spectrometry. Whereas native 2S albumin was digested slowly in 1 h, the reduced and alkylated protein was digested completely within 30 s. These results are discussed in view of the potential allergenicity of Brazil nut 2S albumin.
Subject
Health Toxicology
Food technology
Allergenicity
Denaturation
Pepsin
Protein folding
Protein stability
albumin
guanidine
pepsin A
alkylation
allergenicity
alpha helix
article
Brazil nut
chemical procedures
circular dichroism
energy
food composition
gel electrophoresis
gel permeation chromatography
infrared spectroscopy
mass spectrometry
pH measurement
protein degradation
protein denaturation
protein folding
protein stability
protein structure
temperature dependence
Albumins
Bertholletia
Pepsin A
Plant Proteins
Protein Denaturation
Protein Precursors
Bertholletia excelsa
Ziziphus mauritiana
To reference this document use:
http://resolver.tudelft.nl/uuid:7f985f6c-2d22-4240-854b-e0f85fe20699
DOI
https://doi.org/10.1021/jf0491355
TNO identifier
238305
ISSN
0021-8561
Source
Journal of Agricultural and Food Chemistry, 53 (1), 123-131
Document type
article