Learning from trypsin(ogen) structures: conformational flexibility and functional disorder

Area of Science:

• Biochemistry
• Structural Biology
• Enzymology

Background:

• Trypsin's structure is closely related to chymotrypsin, featuring an active site triad and oxyanion hole.
• The complex of trypsin with basic pancreatic trypsin inhibitor served as a model for proteinase-substrate interactions.
• Early research intertwined trypsin's understanding with its zymogenicity and inhibition.

Purpose of the Study:

• To review the historical and structural understanding of trypsin and its zymogen.
• To highlight the significance of disordered regions in trypsinogen activation and function.
• To discuss trypsin's role as a model for serine proteinases and structure-based drug design.

Main Methods:

• Analysis of crystal structures of trypsinogen.
• Studies on trypsin-inhibitor complexes.
• Design and characterization of trypsin variants for ligand binding and peptide ligation.

Main Results:

• Structural analysis revealed disordered regions in trypsinogen crucial for activation.
• Trypsin variants exhibited unexpected plasticity, complicating protein stability understanding.
• A selected trypsin variant demonstrated zymogen-like properties useful in therapeutic protein modification.

Conclusions:

• Disorder plays a critical role in the functional activation of trypsinogen.
• Trypsin's plasticity presents challenges and opportunities in protein engineering and drug design.
• Seminal works by Bode and Huber profoundly influenced structural biology and our understanding of trypsin.