Characterization of arginine kinase from the caenogastropod Semisulcospira libertina, an intermediate host of Paragonimus westermani

Abstract

Arginine kinase (AK) belongs to the phosphagen kinase (PK) family of enzymes that have a significant role in the maintenance of energy homeostasis. In this study, cDNA of Semisulcospira libertina AK was determined, cloned and the recombinant protein was expressed as fusion protein with maltose-binding protein. The protein has a theoretical molecular mass of 39,412 Da and an estimated isoelectric point (p I) of 6.37. The recombinant enzyme showed high affinity and significant activity only for the substrate L-arginine (Km ¼ 0.53 mM; Vmax ¼ 61.30 mmol/min mg protein). Phylogenetic analyses showed that S. libertina AK clusters with gastropod and cephalopod AKs. Comparison of gene structure showed that all intron positions of S. libertina AK are shared with molluscan AKs. Certain intron positions are also shared with trematode TK and sipunculid HTK. Semisulcospira libertina AK can be utilized in the control of paragonimiasis since it is absent in mammalian hosts.