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From Proteopedia
Crystal structure of the DAP BII hexapeptide complex I
Structural highlights
FunctionDAPB2_PSEMX Exopeptidase that catalyzes the removal of dipeptide units (NH2-P2-P1-) from the free amino termini of oligopeptides and small proteins (PubMed:24598890, PubMed:8892831, PubMed:24827749). Peptide digestion is sequential and substrate recognition is non-specific, with the exception that Pro is not suitable as a P1 residue (PubMed:24827749). Removes many residues of bioactive oligopeptides such as angiotensin I and neuromedin N and cleaves also oxidized insulin B chain. Able to hydrolyze an X-Pro bond, an imido bond. No endopeptidase activity (PubMed:8892831). May play a physiological role in feeding (PubMed:24598890).[1] [2] [3] Publication Abstract from PubMedThe dipeptidyl aminopeptidase BII (DAP BII) belongs to a serine peptidase family, S46. The amino acid sequence of the catalytic unit of DAP BII exhibits significant similarity to those of clan PA endopeptidases, such as chymotrypsin. However, the molecular mechanism of the exopeptidase activity of family S46 peptidase is unknown. Here, we report crystal structures of DAP BII. DAP BII contains a peptidase domain including a typical double beta-barrel fold and previously unreported alpha-helical domain. The structures of peptide complexes revealed that the alpha-helical domain covers the active-site cleft and the side chain of Asn330 in the domain forms hydrogen bonds with the N-terminus of the bound peptide. These observations indicate that the alpha-helical domain regulates the exopeptidase activity of DAP BII. Because S46 peptidases are not found in mammals, we expect that our study will be useful for the design of specific inhibitors of S46 peptidases from pathogens. S46 peptidases are the first exopeptidases to be members of clan PA.,Sakamoto Y, Suzuki Y, Iizuka I, Tateoka C, Roppongi S, Fujimoto M, Inaka K, Tanaka H, Masaki M, Ohta K, Okada H, Nonaka T, Morikawa Y, Nakamura KT, Ogasawara W, Tanaka N Sci Rep. 2014 May 15;4:4977. doi: 10.1038/srep04977. PMID:24827749[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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