3en0

<table><tr><td colspan='2'>[[3en0]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Aphanocapsa_sp._(strain_n-1) Aphanocapsa sp. (strain n-1)]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3EN0 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3EN0 FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr>

<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat"><div style='overflow: auto; max-height: 3em;'>[[1fy2|1fy2]], [[1fye|1fye]]</div></td></tr>

<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">cphB, slr2001 ([https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=1148 Aphanocapsa sp. (strain N-1)])</td></tr>

<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[https://en.wikipedia.org/wiki/Cyanophycinase Cyanophycinase], with EC number [https://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.15.6 3.4.15.6] </span></td></tr>

[[https://www.uniprot.org/uniprot/CPHB_SYNY3 CPHB_SYNY3]] Exopeptidase that catalyzes the hydrolytic cleavage of multi-L-arginyl-poly-L-aspartic acid (cyanophycin; a water-insoluble reserve polymer) into aspartate-arginine dipeptides.

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== Publication Abstract from PubMed ==

Cyanophycin, or poly-L-Asp-multi-L-Arg, is a non-ribosomally synthesized peptidic polymer that is used for nitrogen storage by cyanobacteria and other select eubacteria. Upon synthesis, it self-associates to form insoluble granules, the degradation of which is uniquely catalyzed by a carboxy-terminal-specific protease, cyanophycinase. We have determined the structure of cyanophycinase from the freshwater cyanobacterium Synechocystis sp. PCC6803 at 1.5-A resolution, showing that the structure is dimeric, with individual protomers resembling aspartyl dipeptidase. Kinetic characterization of the enzyme demonstrates that the enzyme displays Michaelis-Menten kinetics with a k(cat) of 16.5 s(-1) and a k(cat)/K(M) of 7.5x10(-6) M(-1) s(-1). Site-directed mutagenesis experiments confirm that cyanophycinase is a serine protease and that Gln101, Asp172, Gln173, Arg178, Arg180 and Arg183, which form a conserved pocket adjacent to the catalytic Ser132, are functionally critical residues. Modeling indicates that cyanophycinase binds the beta-Asp-Arg dipeptide residue immediately N-terminal to the scissile bond in an extended conformation in this pocket, primarily recognizing this penultimate beta-Asp-Arg residue of the polymeric chain. Because binding and catalysis depend on substrate features unique to beta-linked aspartyl peptides, cyanophycinase is able to act within the cytosol without non-specific cleavage events disrupting essential cellular processes.

The structural basis of beta-peptide-specific cleavage by the serine protease cyanophycinase.,Law AM, Lai SW, Tavares J, Kimber MS J Mol Biol. 2009 Sep 18;392(2):393-404. Epub 2009 Jul 8. PMID:19591842<ref>PMID:19591842</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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<div class="pdbe-citations 3en0" style="background-color:#fffaf0;"></div>

== References ==

<references/>

[[Category: Cyanophycinase]]

[[Category: Kimber, M S]]

[[Category: Lai, S W.S]]

[[Category: Law, A M]]

[[Category: Tavares, J]]

[[Category: Beta peptide specific]]

[[Category: Hydrolase]]

[[Category: Serine protease]]