Dissecting the Hydrolytic Activities of Sarcoplasmic Reticulum ATPase in the Presence of Acetyl Phosphate
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arXiv
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| Autori principali: | , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2024
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| _version_ | 1866917579083218944 |
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| author | Soler, F Fortea, MI Lax, A Belda, F Fernandez |
| author_facet | Soler, F Fortea, MI Lax, A Belda, F Fernandez |
| contents | Sarcoplasmic reticulum vesicles and purified Ca$^{2+}$-ATPase hydrolyze acetyl phosphate both in the presence and absence of Ca$^{2+}$. The Ca$^{2+}$-independent activity was fully sensitive to vanadate, insensitive to thapsigargin, and proceeded without accumulation of phosphorylated enzyme. Acetyl phosphate hydrolysis in the absence of Ca$^{2+}$ was activated by dimethyl sulfoxide. The Ca$^{2+}$-dependent activity was partially sensitive to vanadate, fully sensitive to thapsigargin, and associated with steady phosphoenzyme accumulation. The Ca$^{2+}$/P(i) coupling ratio at neutral pH sustained by 10 mm acetyl phosphate was 0.57. Addition of 30% dimethyl sulfoxide completely blocked Ca$^{2+}$ transport and partially inhibited the hydrolysis rate. Uncoupling induced by dimethyl sulfoxide included the accumulation of vanadate-insensitive phosphorylated enzyme. When acetyl phosphate was the substrate, the hydrolytic pathway was dependent on experimental conditions that might or might not allow net Ca$^{2+}$ transport. The interdependence of both Ca$^{2+}$-dependent and Ca$^{2+}$-independent hydrolytic activities was demonstrated. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_17375 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Dissecting the Hydrolytic Activities of Sarcoplasmic Reticulum ATPase in the Presence of Acetyl Phosphate Soler, F Fortea, MI Lax, A Belda, F Fernandez Molecular Networks Sarcoplasmic reticulum vesicles and purified Ca$^{2+}$-ATPase hydrolyze acetyl phosphate both in the presence and absence of Ca$^{2+}$. The Ca$^{2+}$-independent activity was fully sensitive to vanadate, insensitive to thapsigargin, and proceeded without accumulation of phosphorylated enzyme. Acetyl phosphate hydrolysis in the absence of Ca$^{2+}$ was activated by dimethyl sulfoxide. The Ca$^{2+}$-dependent activity was partially sensitive to vanadate, fully sensitive to thapsigargin, and associated with steady phosphoenzyme accumulation. The Ca$^{2+}$/P(i) coupling ratio at neutral pH sustained by 10 mm acetyl phosphate was 0.57. Addition of 30% dimethyl sulfoxide completely blocked Ca$^{2+}$ transport and partially inhibited the hydrolysis rate. Uncoupling induced by dimethyl sulfoxide included the accumulation of vanadate-insensitive phosphorylated enzyme. When acetyl phosphate was the substrate, the hydrolytic pathway was dependent on experimental conditions that might or might not allow net Ca$^{2+}$ transport. The interdependence of both Ca$^{2+}$-dependent and Ca$^{2+}$-independent hydrolytic activities was demonstrated. |
| title | Dissecting the Hydrolytic Activities of Sarcoplasmic Reticulum ATPase in the Presence of Acetyl Phosphate |
| topic | Molecular Networks |
| url | https://arxiv.org/abs/2401.17375 |