Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.27 (thermolysin)
 1,894 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phe5(4-nitro)-bradykinin has been identified as a good synthetic substrate to study the kinetics and mechanism of action of the metalloendopeptidase meprin. No convenient substrate for kinetic analysis of the enzyme had been previously described. HPLC analyses indicated that meprin cleaved bradykinin and nitrobradykinin between Phe5 (or Phe5(NO2)) and Ser6. Reaction rates for bradykinin were determined by quantitative HPLC analyses, whereas rates for nitrobradykinin were measured by continuous monitoring of the spectral change that occurs at 310 nm when the Phe(NO2)-Ser bond is hydrolyzed. For nitrobradykinin and unmodified bradykinin, respectively, Km values were 281 and 425 microM, kcat values were 28 and 22 s-1, and kcat/Km values were 9.7 x 10(4) and 5.1 x 10(4)M-1. The two products of bradykinin hydrolysis were not substrates for the enzyme, but they were inhibitors. The initial rates of hydrolysis of nitrobradykinin increased linearly with enzyme concentration (0.09-2.2 micrograms/ml), and increased linearly with temperature in the range from 15 to 55 degrees C. Hydrolysis of the substrate was optimal at alkaline pH values. The cysteine endopeptidases papain and cathepsin L and the metalloproteases thermolysin, angiotensin-converting enzyme, and neutral endopeptidase (EC 3.4.24.11) also cleaved nitrobradykinin, but at different peptide bonds than meprin. The single cleavage of nitrobradykinin at the Phe(NO2)-Ser bond and the concomitant spectral shift that occurs at alkaline pH makes this a particularly suitable substrate for meprin.
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PMID:Phe5(4-nitro)-bradykinin: a chromogenic substrate for assay and kinetics of the metalloendopeptidase meprin. 196 66

This study investigated short-term (24 h) and long-term (5 wk) systolic blood pressure (SBP)-lowering effects in spontaneously hypertensive rats (SHR) of a 5 kDa membrane pea protein hydrolysate permeate (PPH-5) produced through thermoase hydrolysis of pea protein isolate (PPI). Amino acid analysis showed that the PPH-5 had lower contents of sulfur-containing amino acids than the PPI. Size-exclusion chromatography indicated mainly low molecular weight (<10 kDa) peptides in PPH-5 but not in the PPI. The PPH-5 had renin and angiotensin converting enzyme inhibition IC50 values of 0.57 and 0.10 mg/mL (P < 0.05), respectively, and consisted mainly of peptides with 2 to 6 amino acids. Mass spectrometry analysis revealed mainly hydrophilic tetrapeptide sequences. After a single oral administration (100 mg/kg body weight) to SHR, the unheated PPI showed weakest (P < 0.05) SBP-lowering effect with a -4 mm Hg maximum when compared to -25 mm Hg for heat-treated PPI and -36 mm Hg for PPH-5. Incorporation of the PPH-5 as 0.5% or 1% (w/w) casein substitute in the SHR diet produced maximum SBP reductions of -22 or -26 mm Hg (P < 0.05), respectively after 3 wk. In comparison, the unhydrolyzed PPI produced a maximum SBP reduction of -17 mm Hg also after 3 wk. Potency of the pea products decreased in the 4th and 5th wk, though SBP values of the treated rats were still lower than the untreated control. We conclude that the antihypertensive potency of PPH-5 may have been due to the presence of easily absorbed hydrophilic peptides.
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PMID:Antihypertensive Properties of a Pea Protein Hydrolysate during Short- and Long-Term Oral Administration to Spontaneously Hypertensive Rats. 2703 77