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Determination of proton concentration at cardiolipin-containing membrane interfaces and its relation with the peroxidase activity of cytochrome c

The activities of biomolecules are affected by the proton concentrations at biological membranes. Here, we succeeded in evaluating the interface proton concentration (–log[H(+)] defined as pH′) of cardiolipin (CL)-enriched membrane models of the inner mitochondrial membrane (IMM) using a spiro-rhoda...

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Autores principales: Parui, Partha Pratim, Sarakar, Yeasmin, Majumder, Rini, Das, Sanju, Yang, Hongxu, Yasuhara, Kazuma, Hirota, Shun
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Royal Society of Chemistry 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6889831/
https://www.ncbi.nlm.nih.gov/pubmed/31827756
http://dx.doi.org/10.1039/c9sc02993a
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author Parui, Partha Pratim
Sarakar, Yeasmin
Majumder, Rini
Das, Sanju
Yang, Hongxu
Yasuhara, Kazuma
Hirota, Shun
author_facet Parui, Partha Pratim
Sarakar, Yeasmin
Majumder, Rini
Das, Sanju
Yang, Hongxu
Yasuhara, Kazuma
Hirota, Shun
author_sort Parui, Partha Pratim
collection PubMed
description The activities of biomolecules are affected by the proton concentrations at biological membranes. Here, we succeeded in evaluating the interface proton concentration (–log[H(+)] defined as pH′) of cardiolipin (CL)-enriched membrane models of the inner mitochondrial membrane (IMM) using a spiro-rhodamine-glucose molecule (RHG). According to fluorescence microscopy and (1)H-NMR studies, RHG interacted with the Stern layer of the membrane. The acid/base equilibrium of RHG between its protonated open form (o-RHG) and deprotonated closed spiro-form (c-RHG) at the membrane interface was monitored with UV-vis absorption and fluorescence spectra. The interface pH′ of 25% cardiolipin (CL)-containing large unilamellar vesicles (LUVs), which possess similar lipid properties to those of the IMM, was estimated to be ∼3.9, when the bulk pH was similar to the mitochondrial intermembrane space pH (6.8). However, for the membranes containing mono-anionic lipids, the interface pH′ was estimated to be ∼5.3 at bulk pH 6.8, indicating that the local negative charges of the lipid headgroups in the lipid membranes are responsible for the deviation of the interface pH′ from the bulk pH. The peroxidase activity of cyt c increased 5–7 fold upon lowering the pH to 3.9–4.3 or adding CL-containing (10–25% of total lipids) LUVs compared to that at bulk pH 6.8, indicating that the pH′ decrease at the IMM interface from the bulk pH enhances the peroxidase activity of cyt c. The peroxidase activity of cyt c at the membrane interface of tetraoleoyl CL (TOCL)-enriched (50% of total lipids) LUVs was higher than that estimated from the interface pH′, while the peroxidase activity was similar to that estimated from the interface pH′ for tetramyristoyl CL (TMCL)-enriched LUVs, supporting the hypothesis that when interacting with TOCL (not TMCL), cyt c opens the heme crevice to substrates. The present simple methodology allows us to estimate the interface proton concentrations of complex biological membranes.
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spelling pubmed-68898312019-12-11 Determination of proton concentration at cardiolipin-containing membrane interfaces and its relation with the peroxidase activity of cytochrome c Parui, Partha Pratim Sarakar, Yeasmin Majumder, Rini Das, Sanju Yang, Hongxu Yasuhara, Kazuma Hirota, Shun Chem Sci Chemistry The activities of biomolecules are affected by the proton concentrations at biological membranes. Here, we succeeded in evaluating the interface proton concentration (–log[H(+)] defined as pH′) of cardiolipin (CL)-enriched membrane models of the inner mitochondrial membrane (IMM) using a spiro-rhodamine-glucose molecule (RHG). According to fluorescence microscopy and (1)H-NMR studies, RHG interacted with the Stern layer of the membrane. The acid/base equilibrium of RHG between its protonated open form (o-RHG) and deprotonated closed spiro-form (c-RHG) at the membrane interface was monitored with UV-vis absorption and fluorescence spectra. The interface pH′ of 25% cardiolipin (CL)-containing large unilamellar vesicles (LUVs), which possess similar lipid properties to those of the IMM, was estimated to be ∼3.9, when the bulk pH was similar to the mitochondrial intermembrane space pH (6.8). However, for the membranes containing mono-anionic lipids, the interface pH′ was estimated to be ∼5.3 at bulk pH 6.8, indicating that the local negative charges of the lipid headgroups in the lipid membranes are responsible for the deviation of the interface pH′ from the bulk pH. The peroxidase activity of cyt c increased 5–7 fold upon lowering the pH to 3.9–4.3 or adding CL-containing (10–25% of total lipids) LUVs compared to that at bulk pH 6.8, indicating that the pH′ decrease at the IMM interface from the bulk pH enhances the peroxidase activity of cyt c. The peroxidase activity of cyt c at the membrane interface of tetraoleoyl CL (TOCL)-enriched (50% of total lipids) LUVs was higher than that estimated from the interface pH′, while the peroxidase activity was similar to that estimated from the interface pH′ for tetramyristoyl CL (TMCL)-enriched LUVs, supporting the hypothesis that when interacting with TOCL (not TMCL), cyt c opens the heme crevice to substrates. The present simple methodology allows us to estimate the interface proton concentrations of complex biological membranes. Royal Society of Chemistry 2019-08-06 /pmc/articles/PMC6889831/ /pubmed/31827756 http://dx.doi.org/10.1039/c9sc02993a Text en This journal is © The Royal Society of Chemistry 2019 https://creativecommons.org/licenses/by-nc/3.0/This article is freely available. This article is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported Licence (CC BY-NC 3.0)
spellingShingle Chemistry
Parui, Partha Pratim
Sarakar, Yeasmin
Majumder, Rini
Das, Sanju
Yang, Hongxu
Yasuhara, Kazuma
Hirota, Shun
Determination of proton concentration at cardiolipin-containing membrane interfaces and its relation with the peroxidase activity of cytochrome c
title Determination of proton concentration at cardiolipin-containing membrane interfaces and its relation with the peroxidase activity of cytochrome c
title_full Determination of proton concentration at cardiolipin-containing membrane interfaces and its relation with the peroxidase activity of cytochrome c
title_fullStr Determination of proton concentration at cardiolipin-containing membrane interfaces and its relation with the peroxidase activity of cytochrome c
title_full_unstemmed Determination of proton concentration at cardiolipin-containing membrane interfaces and its relation with the peroxidase activity of cytochrome c
title_short Determination of proton concentration at cardiolipin-containing membrane interfaces and its relation with the peroxidase activity of cytochrome c
title_sort determination of proton concentration at cardiolipin-containing membrane interfaces and its relation with the peroxidase activity of cytochrome c
topic Chemistry
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6889831/
https://www.ncbi.nlm.nih.gov/pubmed/31827756
http://dx.doi.org/10.1039/c9sc02993a
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