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The Ang II (Angiotensin II)-Angiotensin-(1-7) axis of the Renin Angiotensin System encompasses 3 enzymes that form Angiotensin-(1-7) ] directly from Ang II: ACE2 (angiotensin-converting enzyme 2), PRCP (prolylcarboxypeptidase), and POP (prolyloligopeptidase). We investigated their relative contribution to Ang-(1-7) formation in vivo and also ex vivo in serum, lungs, and kidneys using models of genetic ablation coupled with pharmacological inhibitors. In wild-type (WT) mice, infusion of Ang II resulted in a rapid increase of plasma Ang-(1-7). In ACE2 −/− /PRCP −/− mice, Ang II infusion resulted in a similar increase in Ang-(1-7) as in WT (563±48 versus 537±70 fmol/mL, respectively), showing that the bulk of Ang-(1-7) formation in circulation is essentially independent of ACE2 and PRCP. By contrast, a POP inhibitor, Z-Pro-Prolinal reduced the rise in plasma Ang-(1-7) after infusing Ang II to control WT mice. In POP −/− mice, the increase in Ang-(1-7) was also blunted as compared with WT mice (309±46 and 472±28 fmol/mL, respectively P=0.01), and moreover, the rate of recovery from acute Ang II-induced hypertension was delayed (P=0.016). In ex vivo studies, POP inhibition with ZZP reduced Ang-(1-7) formation from Ang II markedly in serum and in lung lysates. By contrast, in kidney lysates, the absence of ACE2, but not POP, obliterated Ang-(1-7) formation from added Ang II. We conclude that POP is the main enzyme responsible for Ang II conversion to Ang-(1-7) in the circulation and in the lungs, whereas Ang-(1-7) formation in the kidney is mainly ACE2-dependent. (Hypertension.

Rhodobacter sphaeroides contains at least two different cytochrome c oxidases. When these bacteria are grown with high aeration, the traditional aa3-type cytochrome c oxidase is present at relatively high levels. However, under microaerophilic growth conditions or when the bacteria are grown photosynthetically, the amount of the aa3-type oxidase is greatly diminished and an alternate cytochrome c oxidase is evident. This alternate oxidase has been purified and characterized. The enzyme consists of three subunits by SDS-PAGE analysis (Mapp 45, 35, and 29 kDa). Two of the three subunits (Mapp 35 and 29 kDa) contain covalently bound heme C. Metal and heme analyses indicate that the oxidase contains heme C, heme B (protoheme IX), and Cu in a ratio of 3:2:1. Cryogenic Fourier transform infrared (FTIR) difference spectroscopy of the CO adduct of the reduced enzyme shows that the oxidase contains a heme-copper binuclear center and, thus, is a member of the heme-copper oxidase superfamily. In contrast to other members of this superfamily, however, this oxidase does not contain either heme O or heme A as a component of the binuclear center, but has heme B at this site. The single equivalent of Cu found in the oxidase is accounted for by the CuB component at the binuclear center. This suggests that this oxidase does not contain CuA, which is found in all other well-characterized cytochrome c oxidases. Both EPR and optical spectroscopic studies are consistent with this conclusion, also indicating that this oxidase does not contain CuA.(ABSTRACT TRUNCATED AT 250 WORDS)

BACKGROUND AND PURPOSE The aggregation of α‐synuclein is connected to the pathology of Parkinson's disease and prolyl oligopeptidase (PREP) accelerates the aggregation of α‐synuclein in vitro. The aim of this study was to investigate the effects of a PREP inhibitor, KYP‐2047, on α‐synuclein aggregation in cell lines overexpressing wild‐type or A30P/A53T mutant human α‐syn and in the brains of two A30P α‐synuclein transgenic mouse strains. EXPERIMENTAL APPROACH Cells were exposed to oxidative stress and then incubated with the PREP inhibitor during or after the stress. Wild‐type or transgenic mice were treated for 5 days with KYP‐2047 (2 × 3 mg·kg−1 a day). Besides immunohistochemistry and thioflavin S staining, soluble and insoluble α‐synuclein protein levels were measured by Western blot. α‐synuclein mRNA levels were quantified by PCR. The colocalization of PREP and α‐synuclein,and the effect of KYP‐2047 on cell viability were also investigated. KEY RESULTS In cell lines, oxidative stress induced a robust aggregation of α‐synuclein,and low concentrations of KYP‐2047 significantly reduced the number of cells with α‐synuclein inclusions while abolishing the colocalization of α‐synuclein and PREP. KYP‐2047 significantly reduced the amount of aggregated α‐synuclein,and it had beneficial effects on cell viability. In the transgenic mice, a 5‐day treatment with the PREP inhibitor reduced the amount of α‐synuclein immunoreactivity and soluble α‐synuclein protein in the brain. CONCLUSIONS AND IMPLICATIONS The results suggest that the PREP may play a role in brain accumulation and aggregation of α‐synuclein, while KYP‐2047 seems to effectively prevent these processes.