1,2-Dichlorobenzene affects the formation of the phosphoenzyme stage during the catalytic cycle of the Ca2 -ATPase from sarcoplasmic reticulumReport as inadecuate




1,2-Dichlorobenzene affects the formation of the phosphoenzyme stage during the catalytic cycle of the Ca2 -ATPase from sarcoplasmic reticulum - Download this document for free, or read online. Document in PDF available to download.

BMC Biochemistry

, 17:5

Protein and enzyme biochemistry

Abstract

Background1,2-Dichlorobenzene 1,2-DCB is a benzene-derived molecule with two Cl atoms that is commonly utilized in the synthesis of pesticides. 1,2-DCB can be absorbed by living creatures and its effects on naturally-occurring enzymatic systems, including the effects on Ca-ATPases, have been poorly studied. Therefore, we aimed to study the effect of 1,2-DCB on the Ca-ATPase from sarcoplasmic reticulum SERCA, a critical regulator of intracellular Ca concentration.

ResultsConcentrations of 0.05–0.2 mM of 1,2-DCB were able to stimulate the hydrolytic activity of SERCA in a medium-containing Ca-ionophore. At higher concentrations 0.25–0.75 mM, 1,2-DCB inhibited the ATP hydrolysis to ~80 %. Moreover, ATP hydrolysis and Ca uptake in a medium supported by K-oxalate showed that starting at 0.05 mM,1,2-DCB was able to uncouple the ratio of hydrolysis-Ca transported. The effect of this compound on the integrity of the SR membrane loaded with Ca remained unaffected. Finally, the analysis of phosphorylation of SERCA by γ-PATP, starting under different conditions at 0° or 25 °C showed a reduction in the phosphoenzyme levels by 1,2-DCB, mostly at 0 °C.

ConclusionsThe temperature-dependent decreased levels of phosphoenzyme by 1,2-DCB could be due to the acceleration of the dephosphorylation mechanism – E2P · Ca2 state to E2 and Pi, which explains the uncoupling of the ATP hydrolysis from the Ca transport.

KeywordsCa-ATPase Sarcoplasmic reticulum Dichlorobenzene Phosphoenzyme  Download fulltext PDF



Author: Javier Vargas-Medrano - Jorge A. Sierra-Fonseca - Luis F. Plenge-Tellechea

Source: https://link.springer.com/







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