Molecular characterization of peptides released from β-lactoglobulin and α-lactalbumin via cardosins A and B

R. M. Barros, F. X. Malcata*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

Crude mixtures of aspartic proteases from flowers of the plant Cynara cardunculus have been studied frequently, as have activities of such enzymes (in pure form) on caseins from bovine, ovine, and caprine sources. This research study addressed pure bovine whey protein as substrates; that is, α-lactalbumin (α-LA) and β-lactoglobulin (α-LG), submitted to hydrolysis by 1 of 2 aspartic proteases (cardosins A and B), previously extracted and purified from C. cardunculus. Samples collected, following incubation at 55°C and pH 5.2, were assayed by fast protein liquid chromatography, reversed phase-high performance liquid chromatography, and tricine-sodium dodecyl sulfate polyacrylamide gel electrophoresis; the major peptides released were then collected and sequenced by Edman degradation. Cardosin B and, to a lesser degree, cardosin A showed proteolytic activity toward α-LA, but the hydrolyzates produced were characterized by distinct peptide profiles. Cardosin B possesses a broad specificity, and produces several hydrophobic peptides (at least 5, with molecular mass in the range 2 to 8 kDa) in the early stages, which eventually become more hydrophilic (with molecular mass below 2 kDa) at later stages of hydrolysis. Cardosin A was found to cleave α-LA at the peptide bonds Phe28-Arg29, Gly54-Tyr55, Ala59-Ile60, Leu71-Phe72, and Leu105-Thr106, whereas cardosin B cleaved Ala19-Glu20, Phe28-Arg29, Glu30-Leu31, Tyr37-Gly38, Trp45-Val46, Phe50-His51, Ala59-Ile60, Ser66-Thr67, Leu71-Phe72, Phe72-Gln73, Gln73-Ile74, Ile78-Trp79, Leul15-Asp116, and Leu124-Ala125. Conversely, cardosins A and B are apparently not active on β-LG.
Original languageEnglish
Pages (from-to)483-494
Number of pages12
JournalJournal of Dairy Science
Volume89
Issue number2
DOIs
Publication statusPublished - Feb 2006

Keywords

  • Aspartic protease
  • Cynara cardunculus
  • Hydrolysis
  • Whey protein

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