Related Experiment Videos
Internally consistent libraries of fluorogenic substrates demonstrate that Kex2 protease specificity is generated by
N C Rockwell1, G T Wang, G A Krafft
1Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor 48109, USA.
Biochemistry
|February 18, 1997
Summary
This study reveals how Kex2 protease from Saccharomyces cerevisiae recognizes its substrates. It precisely identifies key amino acid residues, particularly arginine at P1, crucial for efficient substrate cleavage and enzyme function.
Area of Science:
- Enzymology
- Molecular Biology
- Yeast Genetics
Background:
- Kex2 protease from Saccharomyces cerevisiae is a key enzyme in eukaryotic proprotein processing.
- Understanding substrate recognition is vital for this protease family.
Purpose of the Study:
- Systematically examine Kex2 substrate specificity.
- Clarify interactions responsible for substrate recognition.
Main Methods:
- Utilized internally consistent substrate sets with single/double substitutions.
- Employed fluorogenic peptide substrates (peptidyl-methylcoumarinamides) and internally quenched substrates.
- Performed kinetic analysis to determine enzyme specificity.
Main Results:
- Kex2 exhibits high catalytic efficiency (kcat/KM up to 5 x 10^7 M^-1s^-1) for optimal substrates.
- Kex2 discriminates against Asp at P3 and shows steric constraints at P2.
- Kex2 is highly selective for Arginine (Arg) at the P1 position, with its positive charge stabilizing the transition state by ~6.8 kcal/mol.
Conclusions:
- Kex2 substrate specificity is determined by precise recognition of P1, P2, and P3 residues.
- The P1 arginine residue is critical for Kex2's catalytic activity and substrate binding affinity.