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[New substrates for enteropeptidase. I. Biologically active hepta-nonapeptides]
V V Likhareva1, B V Vas'kovskiĭ, N E Shepel'
1Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, GSP Moscow, 117997 Russia.
Bioorganicheskaia Khimiia
|April 24, 2003
Summary
Enteropeptidase (enterokinase) shows reduced hydrolysis efficiency for specific substrates like angiotensin II and hemoglobin peptides. Elongating these peptides significantly enhances enzyme activity, approaching that of typical substrates.
Area of Science:
- Biochemistry
- Enzymology
- Proteolysis
Context:
- Enteropeptidase (EC 3.4.21.9) is a serine protease crucial for activating digestive enzymes.
- Its substrate specificity involves recognizing specific amino acid sequences, particularly near the cleavage site.
- Understanding enteropeptidase kinetics is vital for protein processing and biotechnology.
Purpose:
- To determine the kinetic parameters (Km, kcat) of enteropeptidase for novel substrates: human angiotensin II, and cattle hemoglobin beta-chain peptides Hb(2-8) and Hb(1-9).
- To compare the hydrolysis efficiency of these substrates with typical synthetic substrates and engineered proteins.
Summary:
- Kinetic analysis revealed significantly lower catalytic efficiency (Km ~10(-3) M, low kcat) for angiotensin II and Hb(2-8) compared to standard enteropeptidase substrates (Km ~10(-4) M).
- Hydrolysis efficiency for these substrates was less than 1% of typical substrates.
- A dramatic increase in catalytic efficiency (kcat = 1510 min-1) was observed for the elongated Hb(1-9) peptide, indicating enhanced substrate recognition upon N- or C-terminal extension.
Impact:
- These findings elucidate the nuanced substrate specificity of enteropeptidase, highlighting the impact of substrate length and sequence context.
- The results provide insights for designing more efficient peptide-based substrates for enteropeptidase in research and industrial applications.
- Demonstrates how subtle modifications in substrate structure can drastically alter enzymatic hydrolysis rates.