We apologize for Proteopedia being slow to respond. For the past two years, a new implementation of Proteopedia has been being built. Soon, it will replace this 18-year old system. All existing content will be moved to the new system at a date that will be announced here.

5xtv

From Proteopedia

Jump to: navigation, search

Crystal Structure of Transketolase in complex with TPP intermediate V from Pichia Stipitis

Structural highlights

5xtv is a 1 chain structure with sequence from Scheffersomyces stipitis CBS 6054. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 0.931Å
Ligands:	, ,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

TKT_PICST Catalyzes the transfer of a two-carbon ketol group from a ketose donor to an aldose acceptor, via a covalent intermediate with the cofactor thiamine pyrophosphate.

Publication Abstract from PubMed

It is theoretically plausible that thiazolium mesomerizes to congeners other than carbene in a low effective dielectric binding site; especially given the energetics and uneven electronegativity of carbene groups. However, such a phenomenon has never been reported. Nine crystal structures of transketolase obtained from Pichia stipitis (TKps) are reported with subatomic resolution, where thiazolium displays an extraordinary ring-bending effect. The bent thiazolium congeners correlate with non-Kekule diradicals because there is no gain or loss of electrons. In conjunction with biophysical and biochemical analyses, it is concluded that ring bending is a result of tautomerization of thiazolium with its non- Kekule diradicals, exclusively in the binding site of TKps. The chemophysical properties of these thiazolium mesomers may account for the great variety of reactivities carried out by thiamine-diphosphate-containing (ThDP) enzymes. The stability of ThDP in living systems can be regulated by the levels of substrates, and hydration and dehydration, as well as diradical-mediated oxidative degradation.

The Mesomeric Effect of Thiazolium on non-Kekule Diradicals in Pichia stipitis Transketolase.,Hsu NS, Wang YL, Lin KH, Chang CF, Lyu SY, Hsu LJ, Liu YC, Chang CY, Wu CJ, Li TL Angew Chem Int Ed Engl. 2018 Feb 12;57(7):1802-1807. doi: 10.1002/anie.201709799., Epub 2018 Jan 15. PMID:29243887^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Hsu NS, Wang YL, Lin KH, Chang CF, Lyu SY, Hsu LJ, Liu YC, Chang CY, Wu CJ, Li TL. The Mesomeric Effect of Thiazolium on non-Kekule Diradicals in Pichia stipitis Transketolase. Angew Chem Int Ed Engl. 2018 Feb 12;57(7):1802-1807. doi: 10.1002/anie.201709799., Epub 2018 Jan 15. PMID:29243887 doi:http://dx.doi.org/10.1002/anie.201709799