Thanks to genetics, now the enzyme can be made in labs

THERE is an ever-rising demand for papain, an enzyme secreted by the papaya plant. Widely used in the preservation of spices, digestive aids and as a contact lens cleaner, it also finds applications in meat tenderization, beer clarification and blood stain removal. However, the extraction of papain from its natural sources and its subsequent purification is quite cumbersome. Researchers working to devise methods to produce papain in the lab, so far, could come up with techniques that yielded low amounts.

A Kolkata team used two things to achieve high yields: a simple genetic alteration and a bacterium. The scientists isolated the propapain-coding gene (propapain is the precursor protein to papain) from young leaves of the papaya plant, altered it slightly and inserted it into the bacterium Escherichia coli. About 1 litre of the bacteria, when cultured, yielded 400 mg of propapain. After that the team took over and in the presence of cysteine (an amino acid) and at an ideal temperature of 50