Definition: In this task, you're given a paragraph from the research paper and your task is to generate a suitable title for the research paper based on the given paper. Under 100 words is a good title length.
Input: Purpose of work The non-structural protein 4 (Nsp4) of porcine reproductive and respiratory syndrome virus (PRRSV) functions as a 3C-like proteinase (3CLpro) and plays a pivotal role in gene expression and replication. We have examined the biochemical properties of PRRSV 3CLpro and identified those amino acid residues involved in its catalytic activity as a prelude to developing anti-PRRSV strategies. The 3C-like proteinase (3CLpro) of porcine reproductive and respiratory syndrome virus (PRRSV) was expressed in Escherichia coli and characterized. The optimal temperature and pH for its proteolytic activity were 8°C and 7.5, respectively. Na ? (1000 mM) and K ? (500 mM) were not inhibitory to its activity but Cu 2? , Zn 2? , PMSF and EDTA were significantly inhibitory. His 39 , Asp 64 and Ser 118 residues were identified to form the catalytic triad of PRRSV 3CLpro by a series of site-directed mutagenesis analysis. Keywords 3C-like proteinase Á Nsp4 Á Porcine reproductive and respiratory syndrome virus

Characterization of the biochemical properties and identification of amino acids forming the catalytic center of 3C-like proteinase of porcine reproductive and respiratory syndrome virus