Immune indices and identical functions of two prophenoloxidases from the haemolymph of green tiger shrimp Penaeus semisulcatus and its antibiofilm activity
In the present study, we purified two prophenoloxidases (proPO) from haemolymph of green tigershrimp,Penaeus semisulcatusby gel fermentation chromatography using blue Sepharose matrix. The twopurified prophenoloxidase macromolecules are of about 76 and 75 kDa determined through SDS-PAGEand named asPenaeus semisulcatusprophenoloxidase I (PSproPO I) andPenaeus semisulcatusproph-enoloxidase II (PSproPO II). It was further characterized by X-Ray Diffraction (XRD), Fourier TransformInfrared Spectroscopy (FTIR), Circular Dichroism (CD) and High Performance Liquid Chromatography(HPLC) analysis. The purified PSproPO I and PSproPO II showed the strongest agglutination titre againsthuman erythrocytes compared to goat RBC. The PSproPO I and PSproPO II showed phagocytic activityagainst yeastSaccharomyces cerevisiaeand encapsulation activity against Sepharose CL 6B beadscompared to CM Sepharose and Sodium alginate beads. The functional analysis of purified PSproPO I andPSproPO II showed enhanced PO activity when added with the triggering molecules such as pathogenassociated molecular patterns (PAMPs), metals and chemicals. In addition, eluted fraction containingPSproPO I and PSproPO II showed antibiofilm activity against Gram positive and Gram negative bacteria.The above results concluded that no significant differences were found between the purified PSproPO Iand PSproPO II immune indices and functions. This study might provide a sensitive platform to under-stand more about the critical roles of PSproPO I and PSproPO II in crustacean immune syste
