Comparison of different extractive procedures for proteins from the edible seaweeds Ulva rigida and Ulva rotundata

Abstract

Proteins have been extracted from the edible seaweeds Ulva rigida Agardh and Ulva rotundata Bliding using classical or enzymatic procedures. The protocols using NaOH under reductive conditions or a two-phase system (PEG/K 2 CO 3 ) produced the best protein yields. The cleavage or the limitation of the linkages between proteins and polysaccharides caused by these experimental conditions probably explains the efficiency of these protocols. In SDS PAGE, the protein fraction obtained after NaOH extraction from U. rotundata is characterised by the presence of three major bands with apparent molecular weights of 45 600, 31 800 and 18 600. The protein fraction from U. rigida presents two specific bands with apparent molecular weights of about 27 000 and 12 000. These fractions are mainly rich in aspartic and glutamic acids, alanine, glycine and contain few hydroxyproline residues (0.91-2.44% total amino acid content). The use of cellulase does not significantly improve the extraction of algal proteins in comparison with the blank procedure (without enzymes). The weak accessibility of the substrates in the intact cell wall could explain these experimental data. The improvement of protein yield after the use of the polysaccharidase mixture (-glucanase, hemicellulase, cellulase) partially confirms this hypothesis.

On the Chemical Profile of Marine Organisms from Coastal Subtropical Environments: Gross Composition and Nitrogen-to-Protein Conversion Factors

“…The concentration of these two AA was higher in the brown alga S. filipendula than in red algae, as previously described by Dawczynski et al (2007). The level of glutamic and aspartic acid together can represent up 26% and 32% of the total AA of the green algae Ulva rigida and U. rotundata (Fleurence et al, 1995). Lourenço et al (2002) showed that values for aspartic and glutamic acid together varied from 20.8 to 31.1% in 19 species of seaweeds.…”

Production of protein extracts from Swedish red, green, and brown seaweeds, Porphyra umbilicalis Kützing, Ulva lactuca Linnaeus, and Saccharina latissima (Linnaeus) J. V. Lamouroux using three different methods

“…Seaweeds have a very tough polysaccharide-rich cell wall and the cell wall mucilage reduces the extractability of proteins (Fleurence et al 1995). The extractability of proteins is affected both by the high viscosity that the polysaccharides exert in a water solution and by the ionic interactions between the cell wall and the proteins (Joubert and Fleurence 2008).…”

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“…However, extraction is one of the main problems in seaweed protein analysis and extraction yields are generally low due to the presence of large amount of polyanionic cell wall mucilage's and phenolic compounds (Admassu, Zhao, Yang, Gasmalla, & Alsir, 2015;Diniz et al, 2011;Fleurence et al, 1995;Wong & Cheung, 2001). After comparing with different classical and enzymatic procedures (eg, an aqueous polymer two-phase system, polysaccharidase, or Tris-HCL buffer), Fleurence et al (1995) concluded that the highest yield of seaweed protein extract could be obtained by the use of sodium hydroxide (NaOH) and 2-mercaptoethanol after an initial aqueous extraction, in which our present protein extraction from commercial dried laver was also done by using this method. Results found in our study for protein content was agreed with the previous report described by (Dawczynski, Schubert, & Jahreis, 2007;Fleurence, 1999a;Wong & Cheung, 2001) in that red and green seaweeds had total protein content within the wide range 10-47% (DW).…”

“…Crude protein was extracted and prepared using the method described (Fleurence, Le Coeur, Mabeau, Maurice, & Landrein, 1995) with slight modification. Briefly, powdered commercial dried laver (particle size<150 µm) was added into deionized water (1:20, powder: water ratio) to allow cell lysis.…”