Indicain, a dimeric serine protease from Morus indica cv. K2

Area of Science:

• Biochemistry
• Enzymology
• Protease research

Background:

• Serine proteases are crucial enzymes with diverse biological roles.
• Plant latexes are a rich source of unique bioactive compounds, including proteases.
• Understanding novel protease characteristics is vital for biotechnological advancements.

Purpose of the Study:

• To purify and characterize a high molecular mass serine protease from Morus indica cv. K2 latex.
• To investigate the enzyme's biochemical properties, stability, and substrate specificity.
• To explore the potential applications of this novel protease.

Main Methods:

• Enzyme purification using ammonium sulfate precipitation, hydrophobic interaction chromatography, and size-exclusion chromatography.
• Molecular mass determination via MALDI-TOF.
• Enzyme activity assays, including caseinolytic activity.
• Inhibition studies using specific protease inhibitors.
• N-terminal sequencing and antibody production for antigenic analysis.

Main Results:

• A homogeneous dimeric serine protease, named indicain, was isolated with a molecular mass of 134.5 kDa.
• The enzyme demonstrated optimal activity at pH 8.5 and 80°C, with significant stability across various conditions.
• Indicain showed broad substrate specificity, comparable to subtilisin-like proteases, and unique antigenic determinants.
• N-terminal sequencing revealed similarity to known plant subtilases.

Conclusions:

• Indicain is a novel, stable, dimeric serine protease from Morus indica latex with unique characteristics.
• Its broad substrate range and stability suggest significant potential for industrial applications in the food and pharmaceutical sectors.
• This study represents the first report of a subtilisin-like dimeric serine protease from this source.