Title
Tentative assignment of the potato serine protease inhibitor group as β-II proteins based on their spectroscopic characteristics
Author
Centraal Instituut voor Voedingsonderzoek TNO
Pouvreau, L.
Gruppen, H.
van Koningsveld, G.A.
van den Broek, L.A.M.
Voragen, A.G.J.
Publication year
2004
Abstract
Potato serine protease inhibitor (PSPI) is the most abundant protease inhibitor group in potato tuber. The investigated PSPI isoforms have a highly similar structure at both the secondary and the tertiary level. From the results described, PSPI is classified as a β-II protein based on (1) the presence in the near-UV spectra of sharp peaks, indicating a rigid and compact protein; (2) the sharp transition from the native to the unfolded state upon heating (only 6°C) monitored by a circular dichroism signal at 222 nm; and (3) the similarity in secondary structure to soybean trypsin inhibitor, a known β-II protein, as indicated by a similar far-UV CD spectrum and a similar amide I band in the IR spectrum. The conformation of PSPI was shown also to be stable at ambient temperature in the pH range 4-7.5. Upon lowering the pH to 3.0, some minor changes in the protein core occur, as observed from the increase of the intensity of the phenylalanine peak in the near-UV CD spectrum. Chemicals / CAS: Serine Proteinase Inhibitors
Subject
β-II protein
pH stability
PSPI
Thermal unfolding
isoprotein
serine proteinase inhibitor
article
controlled study
environmental temperature
heating
nonhuman
pH
potato
protein conformation
protein folding
protein secondary structure
protein stability
protein tertiary structure
thermostability
ultraviolet spectroscopy
Calorimetry, Differential Scanning
Circular Dichroism
Drug Stability
Heat
Protein Folding
Protein Structure, Secondary
Serine Proteinase Inhibitors
Solanum tuberosum
Spectrometry, Fluorescence
Spectrophotometry, Ultraviolet
Glycine max
Solanum tuberosum
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DOI
https://doi.org/10.1021/jf0493932
TNO identifier
238253
ISSN
0021-8561
Source
Journal of Agricultural and Food Chemistry, 52 (52), 7704-7710
Document type
article