| 1. |
- Andersson, Hanna, 1979-, et al.
(author)
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Disulfide cyclized tripeptide analogues of angiotensin IV as potent and selective inhibitors of insulin-regulated aminopeptidase (IRAP)
- 2010
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In: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 0022-2623 .- 1520-4804. ; 53:22, s. 8059-8071
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Journal article (peer-reviewed)abstract
- The insulin-regulated aminopeptidase (IRAP) localized in areas of the brain associated with memory and learning is emerging as a new promising therapeutic target for the treatment of memory dysfunctions. The angiotensin II metabolite angiotensin IV (Ang IV, Val1-Tyr2-Ile3-His4-Pro5-Phe6) binds with high affinity to IRAP and inhibits this aminopeptidase (Ki = 62.4 nM). Furthermore, Ang IV has been demonstrated to enhance cognition in animal models and seems to play an important role in cognitive processes. It is herein reported that displacement of the C-terminal tripeptide His4-Pro5-Phe6 with a phenylacetic acid functionality combined with a constrained macrocyclic system in the N-terminal affords potent IRAP inhibitors that are less peptidic in character than the hexapeptide Ang IV. The best inhibitors in the series, compound 8 and 12, incorporating a 13- and 14-membered disulfide ring system, respectively, and both with a β3-homotyrosine residue (β3hTyr) replacing Tyr2, exhibit Ki values of 3.3 nM and 5.2 nM, respectively.
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| 2. |
- Andersson, Hanna, Dr. 1979-, et al.
(author)
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Ligands to the (IRAP)/AT4 receptor encompassing a 4-hydroxydiphenylmethane scaffold replacing Tyr2
- 2008
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In: Bioorganic & Medicinal Chemistry. - : Elsevier BV. - 0968-0896 .- 1464-3391. ; 16:14, s. 6924-6935
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Journal article (peer-reviewed)abstract
- Analogues of the hexapeptide angiotensin IV (Ang IV, Val(1)-Tyr(2)-Ile(3)-His(4)-Pro(5)-Phe(6)) encompassing a 4-hydroxydiphenylmethane scaffold replacing Tyr(2) and a phenylacetic or benzoic acid moiety replacing His(4)-Pro(5)-Phe(6) have been synthesized and evaluated in biological assays. The analogues inhibited the proteolytic activity of cystinyl aminopeptidase (CAP), frequently referred to as the insulin-regulated aminopeptidase (IRAP), and were found less efficient as inhibitors of aminopeptidase N (AP-N). The best Ang IV mimetics in the series were approximately 20 times less potent than Ang IV as IRAP inhibitors. Furthermore, it was found that the ligands at best exhibited a 140 times lower binding affinity to the membrane-bound IRAP/AT4 receptor than Ang IV. Although the best compounds still exert lower activities than Ang IV, it is notable that these compounds comprise only two amino acid residues and are considerably less peptidic in character than the majority of the Ang IV analogues previously reported as IRAP inhibitors in the literature.
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| 3. |
- Andersson, Hanna, 1979-, et al.
(author)
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Potent Macrocyclic Inhibitors of Insulin-Regulated Aminopeptidase (IRAP) by Olefin Ring-Closing Metathesis
- 2011
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In: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 0022-2623 .- 1520-4804. ; 51, s. 3779-3792
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Journal article (peer-reviewed)abstract
- Macrocyclic analogues of angiotensin IV (Ang IV, Val1-Tyr2-Ile3-His4-Pro5-Phe6) targeting the insulin-regulated aminopeptidase (IRAP) have been designed, synthesized, and evaluated biologically. Replacement of His4-Pro5-Phe6 by a 2-(aminomethyl)phenylacetic acid (AMPAA) moiety and of Val1 and Ile3 by amino acids bearing olefinic side chains followed by macrocyclization provided potent IRAP inhibitors. The impact of the ring size and the type (saturated versus unsaturated), configuration, and position of the carbon–carbon bridge was assessed. The ring size generally affects the potency more than the carbon–carbon bond characteristics. Replacing Tyr2 by β3hTyr or Phe is accepted, while N-methylation of Tyr2 is deleterious for activity. Removal of the carboxyl group in the C-terminal slightly reduced the potency. Inhibitors 7 (Ki = 4.1 nM) and 19 (Ki = 1.8 nM), both encompassing 14-membered ring systems connected to AMPAA, are 10-fold more potent than Ang IV and are also more selective over aminopeptidase N (AP-N). Both compounds displayed high stability against proteolysis by metallopeptidases.
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| 4. |
- Axén, Andreas, et al.
(author)
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Cyclic insulin-regulated aminopeptidase (IRAP)/AT(4) receptor ligands
- 2006
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In: Journal of Peptide Science. - : Wiley. - 1075-2617 .- 1099-1387. ; 12:11, s. 705-713
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Journal article (peer-reviewed)abstract
- The angiotensin IV receptor (AT(4) receptor) is the insulin-regulated aminopeptidase enzyme (IRAP, EC 3.4.11.3). This membrane-spanning enzyme belongs to the M1 family of zinc-dependent metallo-peptidases. It has been proposed that AT4 receptor ligands exert their physiological effects by binding to the active site of IRAP and thereby inhibiting the catalytic activity of the enzyme. The biological activity of a large series of linear angiotensin IV analogs was previously disclosed. Herein, the synthesis and biological evaluation of a series of angiotensin IV analogs, encompassing macrocyclic ring systems of different sizes, are presented. It is demonstrated that disulfide cyclizations of angiotensin IV can deliver ligands with high IRAP/AT4 receptor affinity. One ligand, with an 11-membered ring system (4), inhibited human IRAP and aminopeptidase N (AP-N) activity with similar potency as angiotensin IV but was considerably more stable than angiotensin IV toward enzymatic degradation. The compound provides a promising starting point for further optimization toward more drug-like derivatives. The cyclic constrained analogs allowed us to propose a tentative bioactive conformation of angiotensin IV and it seems that the peptide adopts an inverse gamma-turn at the C-terminal.
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| 5. |
- Axén, Andreas, et al.
(author)
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Small potent ligands to the insulin-regulated aminopeptidase (IRAP)/AT(4) receptor
- 2007
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In: Journal of Peptide Science. - : Wiley. - 1075-2617 .- 1099-1387. ; 13:7, s. 434-444
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Journal article (peer-reviewed)abstract
- Angiotensin IV analogs encompassing aromatic scaffolds replacing parts of the backbone of angiotensin IV have been synthesized and evaluated in biological assays. Several of the ligands displayed high affinities to the insulin-regulated aminopeptidase (IRAP)/AT4 receptor. Displacement of the C-terminal of angiotensin IV with an o-substituted aryl acetic acid derivative delivered the ligand 4, which exhibited the highest binding affinity (Ki = 1.9 nM). The high affinity of this ligand provides support to the hypothesis that angiotensin IV adopts a -turn in the C-terminal of its bioactive conformation.Ligand (4) inhibits both human IRAP and aminopeptidase N-activity and induces proliferation of adult neural stem cells at low concentrations. Furthermore, ligand 4 is degraded considerably more slowly in membrane preparations than angiotensin IV. Hence, it might constitute a suitable research tool for biological studies of the (IRAP)/AT4 receptor.
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| 6. |
- Engen, Karin, et al.
(author)
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Identification of Drug-Like Inhibitors of Insulin-Regulated Aminopeptidase Through Small-Molecule Screening
- 2016
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In: Assay and drug development technologies. - : Mary Ann Liebert Inc. - 1540-658X .- 1557-8127. ; 14:3, s. 180-193
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Journal article (peer-reviewed)abstract
- Intracerebroventricular injection of angiotensin IV, a ligand of insulin-regulated aminopeptidase (IRAP), has been shown to improve cognitive functions in several animal models. Consequently, IRAP is considered a potential target for treatment of cognitive disorders. To identify nonpeptidic IRAP inhibitors, we adapted an established enzymatic assay based on membrane preparations from Chinese hamster ovary cells and a synthetic peptide-like substrate for high-throughput screening purposes. The 384-well microplate-based absorbance assay was used to screen a diverse set of 10,500 compounds for their inhibitory capacity of IRAP. The assay performance was robust with Z-values ranging from 0.81 to 0.91, and the screen resulted in 23 compounds that displayed greater than 60% inhibition at a compound concentration of 10M. After hit confirmation experiments, purity analysis, and promiscuity investigations, three structurally different compounds were considered particularly interesting as starting points for the development of small-molecule-based IRAP inhibitors. After resynthesis, all three compounds confirmed low M activity and were shown to be rapidly reversible. Additional characterization included activity in a fluorescence-based orthogonal assay and in the presence of a nonionic detergent and a reducing agent, respectively. Importantly, the characterized compounds also showed inhibition of the human ortholog, prompting our further interest in these novel IRAP inhibitors.
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