Summary: | The present study was carried out to examine the proteome profile of selected seaweed
species from Sabah waters to explore their nutritional properties. Moisture content was
a major component in seaweed followed by carbohydrate, mineral, and protein. The
results showed significant differences (p<O.05) in proximate compositions and total
phenolic contents among several species of red, green and brown seaweeds. Studies
showed that red seaweed higher in carbohydrate (63 to 74 % dry weight) and protein (6
to 15 % dry weight) content. Brown seaweed higher in mineral (22 to 45 % dry weight)
and fibre (21 to 45 % dry weight) content. Meanwhile, green seaweed higher in total
phenolic content (48 to 52 mg PGE/g dry weight sample). Using caulerpa lentillifera, four
different protocols for protein extraction were evaluated, namely: (i) no protein
precipitation with fractionation; (ii) Trichloroacetic acid (TCA)-acetone precipitation; (iii)
TCA-acetone precipitation with fractionation; and (iv) Phenol extraction methanolammonium
acetate precipitation. Overall, the phenol extraction method gave a higher
protein yield and some protein spots resolved with a satisfactory 2D-PAGE image quality
than the other methods. Thus this method was used to extract total soluble protein from
all 15 seaweed samples. There was a strong positive correlation between crude protein
and total soluble protein concentration (r=O.952; p=O.007) in these fifteen varieties of
seaweed. A distinctive protein pattern was observed in the SDS-PAGE gels between three
different seaweed classes of green, red and brown colours. USing this method of
extraction, it managed to get 2D-PAGE proteome map for three seaweeds species,
namely caulerpa lentillifera, Kappaphycus alvareziivar. aring-aring and Sargassum
polycystum. The image analysis of 2D-PAGE was performed with Progenesis SameSpots
v 4.5 and four sets of comparison of the 2D-PAGE gel image were done, Set 1: caulerpa
lentillifera fronds-CLB vs caulerpa lentillifera stolon-CLT; Set 2: Kappaphycus alvarezi;
small branches-KAK vs Kappaphycus alvarezii big branches-KAB; Set 3: Sargassum
polycystum vacuoles-SPB vs Sargassum polycystum leaves-SPD vs Sargassum
polycystum stolon-SPT; and Set 4: caulerpa lentillifera-Q5 vs Kappaphycus alvarezii -
KAS vs Sargassum polycystum -SPS to detect differentially expressed protein spot.
Results of image analysiS revealed 77 differentially expressed proteins for experiment set
of CLB vs. CL T, 98 differentially expressed proteins for experiment set of KAK vs. KAB,
93 differentially expressed proteins for experiment set of SPB vs. SPD vs. SPT and 148
differentially expressed proteins for experiment set of CLS vs. KAS vs. SPS. Only 20
differentially expressed proteins from all four sets of experiments have been successfully
identified and characterized by using nano-LC-MS/MS (Orbitrap) and Bioinformatics
Software PEAKS Studio 7. Most of the identified proteins were a non-enzyme protein such
as light-harvesting phycobiliprotein, light-harvesting complex, histone, and elongation
factor. The enzyme proteins identified were ribulose bisphosphate carboxylase and
glyceraldehyde-3-phosphate dehydrogenase. Regarding health benefits, the potential
evaluation of the peptide profile results showed that protein extracts from the three
seaweeds species contain peptide sequences with a variety of beneficial health effects.
From among 44 types of biological activity characteristics of peptides, as listed in the
BIOPEP database, motifs with the Dipeptidyl Peptidase IV inhibitors and ACE inhibitory
activity occur most frequently in all protein sequences from the seaweed samples. Others
bioactive peptide present, such as antiOXidant, stimulating, regulating, antiamnestic,
antithrombotic and many other activities. Therefore, this protein raw material, which
currently remains a relatively untapped reservOir, has the potential to act as a resource
for the generation of bioactive peptides with potential health-promoting and diseasepreventing
properties. Hopefully, these findings will contribute towards seaweed protein
utilization as alternative sources of peptide-based nutraceuticals for human health
promotion.
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