Buildup of hydrogen sulfide (H2S), which functions as a signaling molecule but is toxic at high concentrations, is averted by its efficient oxidation by the mitochondrial sulfide oxidation pathway. The first step in this pathway is catalyzed by a flavoprotein, sulfide quinone oxidoreductase (SQR), which converts H2S to a persulfide and transfers electrons to coenzyme Q via a flavin cofactor. All previous studies on human SQR have used detergent-solubilized protein. Here, we embedded human SQR in nanodiscs (ndSQR) and studied highly homogenous preparations by steady-state and rapid kinetics techniques. ndSQR exhibited higher catalytic rates in its membranous environment than in its solubilized state. Stopped-flow spectroscopic data revealed that transfer of the sulfane sulfur from an SQR-bound cysteine persulfide intermediate to a small-molecule acceptor is the rate-limiting step. The physiological acceptor of sulfane sulfur from SQR has been the subject of controversy; we report that the kinetic analysis of ndSQR is consistent with glutathione rather than sulfite being the predominant acceptor at physiologically relevant concentrations of the respective metabolites. The identity of the acceptor has an important bearing on how the sulfide oxidation pathway is organized. Our data are more consistent with the following reaction sequence for sulfide oxidation: H2S→glutathione persulfide→sulfite→sulfate, than with a more convoluted route that would result if sulfite were the primary acceptor of sulfane sulfur. In summary, nanodisc-incorporated human SQR exhibits enhanced catalytic performance, and pre-steady state kinetic characterization of the complete SQR catalytic cycle indicates that GSH serves as the physiologically relevant sulfur acceptor.
from #AlexandrosSfakianakis via Alexandros G.Sfakianakis on Inoreader http://ift.tt/2ropaeK
via IFTTT
Εγγραφή σε:
Σχόλια ανάρτησης (Atom)
Δημοφιλείς αναρτήσεις
-
Publication date: October 2017 Source: International Journal of Biological Macromolecules, Volume 103 Author(s): Mingan Yu, Duqiang Liu, ...
-
Abstract Endurance exercise generates CO 2 via aerobic metabolism; however, its role remains unclear. Exogenous CO 2 by transcutaneous d...
-
FS Teni, AS Surur, A Hailemariam, A Aye, G Mitiku, AE Gurmu, B Tessema Annals of Medical and Health Sciences Research 2015 5(6):454-460 ...
-
Abstract Background Studies exploring the association between physical activity, screen time and sleep and pain usually focus on a limit...
-
RT @caonline : The role of extranodal extension in staging head and neck cancers: http://ift.tt/2qV1As1 #hncsm https://t.co/MxlLX4Olo6 f...
-
One third of adult patients with orthognathic surgery of a prognathic or retrognathic mandible show relapse. The sagittal split osteotomy of...
-
Abstract Wheat germ has an important enzymatic activity, being lipases the enzymes which cause the highest impact in the reduction of shelf...
-
Medicine by Alexandros G. Sfakianakis BioMed Research International BioMed Research InternationalTanshinone IIA Alleviates CCL2-Induced Le...
-
We present a small-scale fading analysis of the vehicular-to-vehicular (V2V) propagation channel at 5.9 GHz when both the transmitter (Tx) a...
Δεν υπάρχουν σχόλια:
Δημοσίευση σχολίου