A structure-based site-directed mutagenesis study on the neurolysin (EC 3.4.24.16) and thimet oligopeptidase (EC 3.4.24.15) catalysis

Neurolysin (EP24.16) and thimet oligopeptidase (EP24.15) are closely related metalloendopeptidases. Site-directed mutagenesis of Tyr(613) (EP24.16) or Tyr(612) (EP24.15) to either Phe or Ala promoted a strong reduction of k(cat)/K-M for both enzymes. These data suggest the importance of both hydroxyl group and aromatic ring at this specific position during substrate hydrolysis by these peptidases. Furthermore, the EP24.15 A607G mutant showed a k(cat)/K-M of 2x10(5) M-1 s(-1) for the Abz-GFSIFRQ-EDDnp substrate, similar to that of EP24.16 (k(cat)/K-M = 3x10(5) M-1 s(-1)) which contains Gly at the corresponding position; the wild type EP24.15 has a k(cat)/K-M of 2.5x10(4) M-1 s(-1) for this substrate. (C) 2003 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.Univ Mogi das Cruzes, CIIB, BR-08780911 Mogi Das Cruzes, SP, BrazilInst Butantan, CAT, Ctr Toxicol Aplicada, BR-05467010 São Paulo, BrazilUniv São Paulo, Inst Ciencias Biomed, Program Biol Celular, Dept Histol & Embriol, BR-05508900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biofis, BR-04044020 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biofis, BR-04044020 São Paulo, BrazilWeb of Scienc

Thimet oligopeptidase (EC 3.4.24.15) key functions suggested by knockout mice phenotype characterization

Thimet oligopeptidase (THOP1) is thought to be involved in neuropeptide metabolism, antigen presentation, neurodegeneration, and cancer. Herein, the generation of THOP1 C57BL/6 knockout mice (THOP1(-/-)) is described showing that they are viable, have estrus cycle, fertility, and a number of puppies per litter similar to C57BL/6 wild type mice (WT). In specific brain regions, THOP1(-/-) exhibit altered mRNA expression of proteasome beta5, serotonin 5HT2a receptor and dopamine D2 receptor, but not of neurolysin (NLN). Peptidomic analysis identifies differences in intracellular peptide ratios between THOP1(-/-) and WT mice, which may affect normal cellular functioning. In an experimental model of multiple sclerosis THOP1(-/-) mice present worse clinical behavior scores compared to WT mice, corroborating its possible involvement in neurodegenerative diseases. THOP1(-/-) mice also exhibit better survival and improved behavior in a sepsis model, but also a greater peripheral pain sensitivity measured in the hot plate test after bradykinin administration in the paw. THOP1(-/-) mice show depressive-like behavior, as well as attention and memory retention deficits. Altogether, these results reveal a role of THOP1 on specific behaviors, immune-stimulated neurodegeneration, and infection-induced inflammation

Meal-induced blood pressure variation and cardiovascular mortality in ambulatory hypertensive elderly patients: preliminary results.

OBJECTIVES: : This prospective cohort study was designed to investigate the prevalence and the prognostic value of postprandial hypotension (PPH) in ambulatory hypertensive elderly patients without overt heart diseases, an issue that has never been evaluated so far. METHODS: : All patients consecutively referred to our cardiologic clinic in the period from January 2005 to August 2009, were enrolled in the study and underwent a 24-h ambulatory arterial blood pressure monitoring (ABPM). PPH has been defined as a decrease in SBP of 20mmHg within 2h after a meal. RESULTS: : Four hundred and one patients were enrolled (mean age 77.7±11 years, males 47.7%). Hypertension was not adequately controlled in 290 (72.3%) patients. PPH was found in 292 of 401 (72.8%) patients. A value of 10mmHg or higher of SD SBP was predictive of PPH, with a sensitivity and specificity of 87 and 57%, respectively. At each meal, patients with higher SBP readings before meal had the greatest decrease in SBP (P<0.001). During the follow-up, 34 patients died for cardiovascular causes. Breakfast BP variation was the most predictive variable of cardiovascular mortality (B=0.020, P=0.04, HR 1.020, IC 1.001-1.040). CONCLUSION: : In our population, PPH was common. A diurnal standard deviation of SBP of 10mmHg or higher was suggestive of its presence. ABPM identified breakfast BP decrease as a possible new risk factor for cardiovascular mortality

Antinociceptive action of hemopressin in experimental hyperalgesia

Endogenous hemorphins, derived from degradation of the beta-chain of hemoglobin, lower arterial blood pressure and exert an antinociceptive action in experimental models of nociception. Hemopressin, derived from the a-chain of hemoglobin, also decreases blood pressure, but its effects on pain have not been studied. In this work, we examined the influence of hemopressin on inflammatory pain. Hemopressin reverted the hyperalgesia induced by either carrageenin or bradykinin when injected concomitantly or 2.5 h after the phlogistic agents. Hemopressin administered systemically also reverted the hyperalgesia induced by carrageenin. Naloxone did not prevent the antinociceptive action of this peptide. These data suggest that hemopressin inhibits peripheral hyperalgesic responses by mechanisms independent of opioid receptor activation. (C) 2004 Elsevier Inc. All rights reserved.26343143

Dynamics of catalysis and inhibition in oligopeptidases: natural peptide structures as promising antihypertensive agents.

Short Abstract: Molecular modeling, combined with docking and molecular dynamics experiments was used to study the dynamics of catalysis/inhibition in ?druggable? human Oligopeptidases. The dynamics of ligand recognition and structural determinants for selective inhibition of these enzymes lead us to propose more selective oligopeptidase inhibitors with improved stability and pharmacological profile.ISMB, X-MEETING 2006. Poster E-8