LAUSR

BACKGROUND Peptidyl-prolyl cis-trans isomerisation (PPIases) enzyme plays a vital role in protein folding. It catalyses the cis-trans isomerisation of peptide bonds, an essential step for newly synthesized protein to acquire its correct functional conformation in both prokaryotes and eukaryotes. OBJECTIVE The present study showed the biochemical and molecular characterisation of cyclophilins (PpiB), a type of peptidyl-prolyl isomerases proteins from the pathogenic bacteria Salmonella Typhimurium. METHODS Salmonella Typhimurium is one of the leading serovars responsible for human and animal salmonellosis globally, with the majority of human cases originating through the food chain. Here successful expression and purification of PpiB protein have been demonstrated and LC-MS based analyses showed high protein score and similarity with other PPi protein. Further the enzymatic activity of the purified recombinant PpiB was determined using Succinyl-Ala-Phe-Pro-Phe-p nitroanilide as substrate and enzyme-catalysed reaction. RESULT Km and Vmax were calculated and found to be Vm = 1.023 ± .06400 min/µg, Km = 0.6219 ± 0.1701 µM, respectively.We have reported for the first time the presence of Salmonella PPIase-B (PpiB) protein isoforms in salmonella genome having PPi activity. CONCLUSION Taken together, our data clearly showed that Salmonella Cyclophilin B (PpiB) protein is active and involved in diverse biological processes and highly similar to the different domain of Cyclophilin proteins.