SPECTROSCOPIC CHARACTERIZATION OF THE LIPID-BINDING PROPERTIES OF WHEAT PUROINDOLINES

Citation
M. Kooijman et al., SPECTROSCOPIC CHARACTERIZATION OF THE LIPID-BINDING PROPERTIES OF WHEAT PUROINDOLINES, Journal of cereal science, 26(2), 1997, pp. 145-159
Citations number
18
Categorie Soggetti
Food Science & Tenology
Journal title
ISSN journal
07335210
Volume
26
Issue
2
Year of publication
1997
Pages
145 - 159
Database
ISI
SICI code
0733-5210(1997)26:2<145:SCOTLP>2.0.ZU;2-L
Abstract
The lipid-binding properties of wheat puroindolines (PINs) make these proteins likely candidates to play an important role in the stability of lipid films in die gas cells of bread dough, an important aspect of bread making. Therefore, the interaction between PINs and water-solub le model lipids was investigated by fluorescence emission and circular dichroism (CD) spectroscopy. The secondary structure of PIN-a and PIN -b in solution, as determined by far-UV CD measurements, resembled tha t of plant non-specific lipid transfer protein (LTP). However, PINs co ntain a tryptophan-rich loop located at the exterior of the protein. I t was shown by fluorescence emission spectroscopy and near UV CD spect roscopy that this domain is involved in the lipid binding. Fluorescenc e titration experiments of PIN and its synthetic tryptophan-rich domai ns with the zwitterionic lipid n-hexadecylphosphocholine (C16PN) revea led that the binding was cooperative. For the binding of the charged l ipids, n-hexadecacylphosphoglycol (C16PG) and hexadecyl-trimethylammon iumbromide (CTAB), a clear effect of ionic strength of the solution wa s obtained. Organisation of lipids into micelles Tvas not a prerequisi te For binding to PINs. Most likely, wheat PIN binds to monomeric lipi d molecules via its tryptophan-rich domain, rendering the protein more hydrophobic. The overall secondary structure of wheat PINs did not ch ange significantly upon binding to lipids. (C) 1997 Academic Press Lim ited.