Properties of a milk clotting protease isolated from fruits of Bromelia balansae Mez

Abstract

Unripe fruit extracts of Bromelia balansae Mez (Bromeliaceae), whose principal endopeptidase is balansain I (isolated for anion exchange chromatography: pI = 5.45, molecular weight = 23192), exhibit a pH profile with a maximum activity around pH 9.0 and are inhibited only by cysteine peptidases inhibitors. The alanine and glutamine derivatives of N-alpha-carbobenzoxy-L-amino acid p-nitrophenyl esters were strongly preferred by the enzyme. Enzymatic hydrolysis of milk and soy proteins yield characteristic patterns at pH 9.0. The N-terminal sequence showed a very high homology (85-90%) with other known Bromeliaceae endopeptidases.