View source for 6hqj


==apo-form of polyphenol oxidase from Solanum lycopersicum==
<StructureSection load='6hqj' size='340' side='right'caption='[[6hqj]], [[Resolution|resolution]] 1.80&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6hqj]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Solanum_lycopersicum Solanum lycopersicum]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6HQJ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6HQJ FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.802&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=6hqj FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6hqj OCA], [https://pdbe.org/6hqj PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6hqj RCSB], [https://www.ebi.ac.uk/pdbsum/6hqj PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6hqj ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/PPOA_SOLLC PPOA_SOLLC] Catalyzes the oxidation of mono- and o-diphenols to o-diquinones.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Polyphenol oxidases (PPOs) contain the structurally similar enzymes tyrosinases (TYRs) and catechol oxidases (COs). Two cDNAs encoding pro-PPOs from tomato (Solanum lycopersicum) were cloned and heterologously expressed in Escherichia coli. The two pro-PPOs (SlPPO1-2) differ remarkably in their activity as SlPPO1 reacts with the monophenols tyramine (kcat = 7.94 s(-1)) and phloretin (kcat = 2.42 s(-1)) and was thus characterized as TYR, whereas SlPPO2 accepts only diphenolic substrates like dopamine (kcat = 1.99 s(-1)) and caffeic acid (kcat = 20.33 s(-1)) rendering this enzyme a CO. This study, for the first time, characterizes a plant TYR and CO originating from the same organism. Moreover, X-ray structure analysis of the latent holo- and apo-SlPPO1 (PDB: 6HQI and 6HQJ) reveals an unprecedented high flexibility of the gatekeeper residue phenylalanine (Phe270). Docking studies showed that depending on its orientation the gatekeeper residue could either stabilize and correctly position incoming substrates or hinder their entrance into the active site. Furthermore, phloretin, a substrate of SIPPO1 (Km = 0.11 mM), is able to approach the active centre of SlPPO1 with both phenolic rings. Kinetic and structural results indicate that phloretin could act as a natural substrate and connote the participation of PPOs in flavonoid-biosynthesis.

Biochemical and structural characterization of tomato polyphenol oxidases provide novel insights into their substrate specificity.,Kampatsikas I, Bijelic A, Rompel A Sci Rep. 2019 Mar 11;9(1):4022. doi: 10.1038/s41598-019-39687-0. PMID:30858490<ref>PMID:30858490</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6hqj" style="background-color:#fffaf0;"></div>

==See Also==
*[[Tyrosinase 3D structures|Tyrosinase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Solanum lycopersicum]]
[[Category: Bijelic A]]
[[Category: Kampatsikas I]]
[[Category: Rompel A]]