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Fractionation of gliadin hydrolysates in water‐ethanol by ultrafiltration with modified or unmodified membranes
Author(s) -
Bérot Serge,
Chaufer Bernard,
Basso Yannick,
Legay Cécile,
Popineau Yves
Publication year - 1999
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(19990320)62:6<649::aid-bit4>3.0.co;2-r
Subject(s) - chemistry , diafiltration , membrane , chromatography , hydrolysate , ultrafiltration (renal) , ionic strength , hydrolysis , fractionation , permeation , elution , biochemistry , aqueous solution , organic chemistry , microfiltration
Ultrafiltration was applied to the fractionation of neutral vs. charged peptides of similar size. The peptides, produced from gliadins, a major fraction of wheat storage proteins, were obtained by limited hydrolysis with α‐chymotrypsin in water‐ethanol 80/20 (v/v). Peptides, according to their elution by RP‐HPLC, were quasi‐neutral (repetitive peptides) irrespective of pH, or positively charged (nonrepetitive peptides) at pH below 5. The transmission through the membranes of the nonrepetitive peptides was less (until sevenfold) than that of the repetitive ones, because of the role of electrostatic repulsion involved in the retention of charged solutes. The difference of transmission was more efficient at acidic pH (3) and low ionic strength with inorganic membranes and in a wider range of pH and ionic strength with membranes modified by coating of positively charged polymers (polyvinylimidazole PVI, polyethyleneimine PEI). A continuous diafiltration process using an inorganic membrane of low molecular cut‐off permitted the selective enrichment of the retentate in nonrepetitive peptides (up to 80%) and of the permeate in repetitive peptides (up to 88%) from hydrolysate feed containing about 60/40% of repetitive and nonrepetitive peptides, respectively, with a diafiltration volume of 4. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 62: 649–658, 1999.