Purification, characterization, and molecular cloning of a chitinase from the seeds of Benincasa hispida

A chitinase was purified from the seeds of Benincasa hispida, a medicinal p lant also called white gourd, and a member of the Cucurbitacene family. Pur ification was done by using a procedure consisting of only two fractionatio n steps: an acid denaturation step followed by ion-exchange chromatography. The sequence of the N-terminal forty amino acid residues was analyzed and the sequence indicated that the enzyme is a class III chitinase. The enzyme , which is a basic chitinase, is one of at least five chitinases detected i n the seed extract of B. hispida, Like other class III chitinases, this enz yme also has lysozyme activity. A genomic clone of the gene encoding the en zyme was isolated and sequenced. The gene has the potential to encode a pro tein of 301 amino acid residues. The deduced amino acid sequence of the pro tein, as expected from the N-terminal amino acid sequence, shares high degr ees of similarity with other class III chitinases.