| Summary: | The antimicrobial peptide is a new potential antibiotic type that can be isolated not only from free peptides but also
peptides from hydrolyzed protein with proteolytic enzymes. The protein of jatropha seed is toxic due to RIP, ribosome-
inactivating protein, and a potential source of AMP. Trifluoroacetic acid was used to isolate jatropha seed protein. The protein was hydrolyzed using trypsin and the hydrolysate separated with a cation exchange solid phase extraction (SPE) column. Each fraction was tested for antimicrobial activity and resulted in the pH 3 and pH 4 fractions being able to inhibit bacterial growth against Staphylococcus aureus (Gram-positive bacteria) and Escherichia coli (Gramnegative bacteria). The pH 3 fraction has IC50 value 17.95 μg/mL to E. coli and 17.03 μg/mL to S. aureus, while the pH fraction has IC50 value 37.30 μg/mL and 95.31 μg/mL respectively. There are three peptides with amino acid sequences of GAGLVPKR, MGACCSKEPSFAEGR and VALASLLSQPLPQISDK identified from those fractions. These peptides potentially inhibit bacterial growth through membrane destabilization mechanism, due to their amphipathic and ionic properties.
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