Yeast dipeptidase: active site mapping by kinetic studies with substrates and substrate analogs

Area of Science:

• Biochemistry
• Enzymology

Background:

• Yeast dipeptidase plays a role in peptide metabolism.
• Detailed characterization of its active site is essential for understanding enzyme function.

Purpose of the Study:

• To elucidate the structural and functional characteristics of the yeast dipeptidase active site.
• To investigate substrate binding and specificity through kinetic analysis.

Main Methods:

• Kinetic studies using various dipeptide substrates and analogs.
• Development of computer programs for initial velocity calculation from progress curves.
• Nonlinear regression analysis for kinetic parameter evaluation.

Main Results:

• A free carboxyl group is essential for substrate binding, with strict conformational requirements.
• The terminal ammonium ion's spatial arrangement is less critical for binding.
• Substrate specificity is determined by interactions with hydrophobic subsites for C-terminal and N-terminal side chains.
• Inhibition kinetics suggest an ordered product release mechanism.

Conclusions:

• The yeast dipeptidase active site possesses distinct subsites with specific hydrophobic properties for substrate recognition.
• Understanding these interactions provides insights into enzyme mechanism and substrate selectivity.