3qum | pdb_00003qum

Crystal structure of human prostate specific antigen (PSA) in Fab sandwich with a high affinity and a PCa selective antibody

spinqualitylabelsall models 3qum, resolution 3.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3qum is a 10 chain structure with sequence from Homo sapiens and Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: A2G, FUC, GAL, MAN, NAG NonStd Res: SIA Related: 2zch, 2zck, 2zcl Activity: Semenogelase, with EC number 3.4.21.77 Resources: FirstGlance, OCA, RCSB, PDBsum Function [KLK3_HUMAN] Hydrolyzes semenogelin-1 thus leading to the liquefaction of the seminal coagulum. Publication Abstract from PubMed Human prostate-specific antigen (PSA or human kallikrein-related peptidase 3) present in small quantities in the sera of healthy men becomes elevated in prostate cancer (PCa) and other prostate disorders. The ability to identify the free PSA fraction associated with PCa could increase the reliability of the PSA diagnostic test. Here we present the crystal structure of human PSA from seminal fluid in a sandwich complex with two monoclonal antibodies (mAbs). MAb 5D5A5 captures total PSA with exceptionally high affinity, and mAb 5D3D11 selectively discriminates between free PSA subforms that are more abundant in sera from patients with PCa. Although the antigen is not of seric origin, several insights into cancer diagnosis can be discerned from this complex. MAb 5D3D11 recognizes a PSA conformation different from that previously reported. Interacting with the kallikrein loop, the PSA N-linked glycan attached to asparagine 61 is an uncommonly complex sialated triantennary chain. O-Linked glycosylation is observed at threonine 125. The description of how PSA subforms in prostatic fluid can be discriminated using pairs of antibodies is a first step in the design of new strategies that are capable of real discrimination among PSA subforms, which will lead to the formulation of more reliable diagnostic tests. In a companion article [Muller, B. H., Savatier, A., L'Hostis, G., Costa, N., Bossus, M., Michel, S., et al. (2011). In vitro affinity maturation of an anti-PSA antibody for prostate cancer diagnostic assay. J. Mol. Biol.], we describe engineering efforts to improve the affinity of mAb 5D3D11, a first step towards such goal. Crystal Structure of Human Prostate-Specific Antigen in a Sandwich Antibody Complex.,Stura EA, Muller BH, Bossus M, Michel S, Jolivet-Reynaud C, Ducancel F J Mol Biol. 2011 Oct 20. PMID:22037582 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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