Identification of a Peptide Produced by Bifidobacterium longum CECT 7210 with Antirotaviral Activity

Chenoll, Empar; Casinos, Beatriz; Bataller, Esther; Buesa, Javier; Ramón, Daniel; Genovés, Salvador; Fábrega, Joan; Rivero Urgell, Montserrat; Moreno Muñoz, José A.

As human rotavirus proliferation is thought to be inhibited by the 11-mer peptide (found in cow milk β-casein), we evaluated a hypothetical mechanism whereby the peptide is released by a potential supernatant protease activity, which hydrolyses the casein present in MRS broth. To check this hypothesis, a strategy was adopted to purify and identify the potential enzyme. First of all, supernatant was chromatographically purified and the final protease-positive fraction was electrophoresed. The single 47 KDa band present in the SDS-PAGE gel was separated and analyzed by MALDI-TOF peptide mass fingerprinting. The band was identified as "MalE-type ABC sugar transport system periplasmic component, " being the highest homology with sequence gi| 189440352 (MalE-type ABC sugar transport system periplasmic component from B. longum DJO10A), which has a molecular weight of 47.155 KDa. In order to evaluate the formation of 11-mer peptide from β-casein by the activity of the purified protease, a hydrolysis assay was performed using the purified protease as enzyme and β-casein as substrate. After 48 h of hydrolysis, peptide quantification by HPLC showed an efficiency of 28 ± 1 µg of 11-mer peptide/mL.