1b2i
From Proteopedia
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KRINGLE 2 DOMAIN OF HUMAN PLASMINOGEN: NMR SOLUTION STRUCTURE OF TRANS-4-AMINOMETHYLCYCLOHEXANE-1-CARBOXYLIC ACID (AMCHA) COMPLEX
Contents |
Overview
The kringle 2 (K2) module of human plasminogen (Pgn) binds L-lysine and, analogous zwitterionic compounds, such as the antifibronolytic agent, trans-(aminomethyl)cyclohexanecarboxylic acid (AMCHA). Far-UV CD and NMR, spectra reveal little conformational change in K2 upon ligand binding., However, retarded (1)H-(2)H isotope exchange kinetics induced by AMCHA, indicate stabilization of the K2 conformation by the ligand. Assessment of, secondary structure content from CD spectra yields approximately 26%, beta-STRAND, approximately 13% beta-TURN, approximately 15% 3(1)-HELIX, and approximately 6% 3(10)-HELIX. The NMR solution conformation of the K2, domain complexed to AMCHA has been determined [heavy atom rmsd = 0.49 +/-, 0.09A (BACKBONE) AND 1.02+/- 0.08 (ALL)]. The K2 molecule has overall, dimensions of approximately 34.5A times approximately 33.4A times, approximately 22.7A . Analogous with the polypeptide outline of homologous, domains, K2 contains three short antiparallel beta-sheets (paired strands, 15-16/20-21, 24-25/48-49, and 62-64/72-74) and four defined beta-turns, (residues 6-9, 16-19, 53-56, AND 67-70). Consistent with the CD analysis, albeit novel in the context of kringle folding, the NMR structure reveals, an unpaired beta-strand structured by residues 30-32, a turn of, 3(10)-helix compromising residues 38-41, and a 3(1)-helix for residues, 21-24 and 74-79. We also identify alignable 3(1)-helices in previously, reported homologous kringle structures. Rather high order parameter S(2), values (<S(2)>= approximately 0.85 +/- 0.04) characterize the K2 backbone, dynamics. The lowest flexibility is observed for the two inner loop, segments of residues 51-63 AND 63-75 (<S(2)>= approximately 0.86-0.87 +/-, 0.03). Overhauser connectivities reveal close hydrophobic contacts of the, ligand ring with side chains of Tyr(36), Trp(62), Phe(64), Trp(72), AND, Leu(74). In most K2 structures, the N atom of AMCHA places itself, approximately 3.9 and 4.4A from the anionic groups of Glu(57) and Asp(55), respectively, while its carboxylate group, H-bonded to the Tyr(36) side, chain OH(eta), ion-pairs the Arg(71) guanidinium group. Consistent with, the preference of K2 for binding 5-aminopentanoic acid over, 6-aminohexanoic acid, the positions of the ionic centers within the K2, binding site approach each other approximately 1A closer relative to what, is observed in lysine binding sites of homologous Pgn modules.
Disease
Known diseases associated with this structure: Conjunctivitis, ligneous OMIM:[173350], Plasminogen Tochigi disease OMIM:[173350], Plasminogen deficiency, types I and II OMIM:[173350], Thrombophilia, dysplasminogenemic OMIM:[173350]
About this Structure
1B2I is a Single protein structure of sequence from Homo sapiens with AMH as ligand. Active as Plasmin, with EC number 3.4.21.7 Full crystallographic information is available from OCA.
Reference
Solution structure and dynamics of the plasminogen kringle 2-AMCHA complex: 3(1)-helix in homologous domains., Marti DN, Schaller J, Llinas M, Biochemistry. 1999 Nov 30;38(48):15741-55. PMID:10625440
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