Insights into cathepsin-B activity in mature dentin matrix

Area of Science:

• Biochemistry
• Enzymology
• Dental research

Background:

• Cysteine proteases are lysosomal enzymes.
• Under certain conditions, they can be secreted extracellularly.
• They participate in protein turnover.

Purpose of the Study:

• Investigate the role of cathepsin B in the gelatinolytic activity of dentin matrices.
• Determine the contribution of cathepsin B to matrix turnover at neutral pH.

Main Methods:

• Enzyme extraction from human dentin powder.
• Identification of proteases (cathepsin B, MMP-2, MMP-9) via immunoblotting.
• Activity assays using fluorogenic substrates and inhibitors at neutral pH.
• Mass spectrometry for cleavage point determination.
• Reverse zymography for cathepsin B gelatinolytic activity.

Main Results:

• Cathepsin B, MMP-2, and MMP-9 were identified in dentin extracts.
• Enzyme activity was higher without inhibitors, indicating protease involvement.
• Cathepsin B demonstrated significant gelatinolytic activity.

Conclusions:

• Cathepsin B contributes to host-derived gelatinolytic activity in mature dentin.
• Along with MMP-2 and MMP-9, cathepsin B is involved in dentin matrix turnover.
• These activities occur at physiological, neutral pH.