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Because of their abundance, resistance to proteolysis, rapid aggregation and neurotoxicity, N-terminally truncated and, in particular, pyroglutamate (pE)-modified A[beta] peptides have been suggested as being important in the initiation of pathological cascades resulting in the development of Alzheimer's disease (1-6). We found that the N-terminal pE-formation is catalyzed by glutaminyl cyclase in vivo. Glutaminyl cyclase expression was upregulated in the cortices of individuals with Alzheimer's disease and correlated with the appearance of pE-modified A[beta]. Oral application of a glutaminyl cyclase inhibitor resulted in reduced A[[beta].sub.3(pE)-42] burden in two different transgenic mouse models of Alzheimer's disease and in a new Drosophila model. Treatment of mice was accompanied by reductions in A[[beta].sub.3(pE)-40/42], diminished plaque formation and gliosis and improved performance in context memory and spatial learning tests. These observations are consistent with the hypothesis that A[[beta].sub.3(pE)-42] acts as a seed for A[beta] aggregation by self-aggregation and co-aggregation with A[[beta].sub.1-40/42]. Therefore, A[[beta].sub.3(pE)-40/42] peptides seem to represent A/3 forms with exceptional potency for disturbing neuronal function. The reduction of brain pE-A[beta] by inhibition of glutaminyl cyclase offers a new therapeutic option for the treatment of Alzheimer's disease and provides implications for other amyloidoses, such as familial Danish dementia., The brains of individuals with Alzheimer's disease are characterized by the presence of neurofibrillary tangles and by deposits of A[beta] in neocortical brain structures (1). Sequential [beta]- and [gamma]-secretase cleavage [...]

Murine glutaminyl cyclase (mQC) is identified in the insulinoma cell line beta-TC 3 by determination of enzymatic activity and RT-PCR. The results with newly cloned and analyzed mQC support that all mammaalian QCs are zinc-dependent catalysts.

Transmission electron microspray (TEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), X-ray scattering, rheological measurements, and dynamic light scattering (DLS) were used to investigate the temperature-dependent self-assembly of the single-chain bolaamphiphile dotriacontan-1,1'-diyl-bis[2-(trimethylammino)ethyl phosphate] (PC-C32-PC). A feature of the self-assembly process is that it is driven solely by hydrophobic interactions of the long alkyl chains.

Modified amyloid β (Aβ) peptides represent major constituents of the amyloid deposits in Alzheimer’s disease and Down’s syndrome. In particular, N-terminal pyroglutamate (pGlu) following truncation renders Aβ more stable, increases hydrophobicity and the aggregation velocity. Recent evidence based on in vitro studies suggests that the cyclization of glutamic acid, leading to pGlu-Aβ, is catalyzed by the enzyme glutaminyl cyclase (QC) following limited proteolysis of Aβ at the N-terminus. Here, we studied the pGlu-formation by rat QC in vitro as well as after microinjection of Aβ(1–40) and Aβ(3–40) into the rat cortex in vivo/ in situ with and without pharmacological QC inhibition. Significant pGlu-Aβ formation was observed following injection of Aβ(3–40) after 24 h, indicating a catalyzed process. The generation of pGlu-Aβ from Aβ(3–40) was significantly inhibited by intracortical microinjection of a QC inhibitor. The study provides first evidence that generation of pGlu-Aβ is a QC-catalyzed process in vivo. The approach per se offers a strategy for a rapid evaluation of compounds targeting a reduction of pGlu formation at the N-terminus of amyloid peptides. [ABSTRACT FROM AUTHOR]

Inhibition of DPP IV has been shown to abrogate the stress-related increase in murine abortions and a concomitant increase in γ-interferon. The aim of the present study was to investigate a potential impact of the DPP IV inhibitor Isoleucine Cyanopyrrolidide on the expression of surface antigens involved in T-cell responses. DBA/2-mated CBA mice were stressed on day 5.5 of pregnancy and received injections of a DPP IV inhibitor. On day 13 of gestation, the animals were sacrificed and the percentage of abortions was determined. As shown before, stress failed to boost the abortion rate in mice receiving the DPP IV inhibitor. In stressed animals, a lower surface density of CTLA-4 on decidual CD26-positive lymphocytes was observed than in non-stressed animals. Inhibition of DPP IV restored CTLA-4 surface density to normal and decreased surface expression of CD26 and CD28 on decidual lymphocytes irrespective of stress exposure. These observations suggest that a modulation of T-cell surface antigens expression due to inhibition of DPP IV activity may contribute to the potent anti-abortogenic effect observed here. [Copyright &y& Elsevier]

The first effective inhibitors for human glutaminyl cyclase (QC) are described. The structures are developed by applying a ligand-based optimization approach starting from imidazole. Screening of derivatives of that heterocycle led to compounds of the imidazol-1-yl-alkyl thiourea type as a lead scaffold. A library of thiourea derivatives was synthesized, resulting in an inhibitory improvement by 2 orders of magnitude, leading to 1-(3-(1H-imidazol-1-yl)propyl)-3-(3,4-dimethoxyphenyl)thiourea as a potent inhibitor. Systematic exploitation of the scaffold revealed a strong impact on the inhibitory efficacy and resulted in the development of imidazole-propyl-thioamides as another new class of potent inhibitors. A flexible alignment of the most potent compounds of the thioamide and thiourea class and a QC substrate revealed a good match of characteristic features of the molecules, which suggests a similar binding mode of both inhibitors and the substrate to the active site of QC.

Legumain is a lysosomal cysteine peptidase specific for an asparagine residue in the P1-position. It has been classified as a member of clan CD peptidases due to predicted structural similarities to caspases and gingipains. So far, inhibition studies on legumain are limited by the use of endogenous inhibitors such as cystatin C. A series of Michael acceptor inhibitors based on the backbone Cbz-L-Ala-L-Ala-L-Asn (Cbz= benzyloxycarbonyl) has been prepared and resulted in an irreversible inhibition of porcine legumain. Variation of the molecular size within the 'war head' revealed the best inhibition for the compound containing the allyl ester (kobs/I=766 M(-1) s(-1)). To overcome cyclisation between the amide moiety of the Asn residue and the 'war head', several asparagine analogues have been synthesised. Integrated in halomethylketone inhibitors, azaasparagine is accepted by legumain in the P1-position. The most potent inhibitor of this series, Cbz-L-Ala-L-Ala-AzaAsn-chloromethylketone, displays a k(obs)/I value of 139,000 M(-1) s(-1). Other cysteine peptidases, such as papain and cathepsin B, are not inhibited by this compound at concentrations up to 100 microM. The synthetic inhibitors described here represent useful tools for the investigation of the structural and physiological properties of this unique asparagine-specific peptidase.