Efficient DNP NMR of membrane proteins: sample preparation protocols, sensitivity, and radical location
Although dynamic nuclear polarization (DNP) has dramatically enhanced solid-state NMR spectral sensitivities of many synthetic materials and some biological macromolecules, recent studies of membrane-protein DNP using exogenously doped paramagnetic radicals as polarizing agents have reported varied...
| Main Authors: | , , , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
Springer Netherlands
2016
|
| Online Access: | http://hdl.handle.net/1721.1/103041 https://orcid.org/0000-0002-1801-924X https://orcid.org/0000-0003-3002-6298 https://orcid.org/0000-0001-5255-5858 https://orcid.org/0000-0002-0022-2637 |
| _version_ | 1826198398846369792 |
|---|---|
| author | Liao, Shu-Yu Lee, Myungwoon Wang, Tuo Sergeyev, Ivan V. Hong, Mei |
| author2 | Massachusetts Institute of Technology. Department of Chemistry |
| author_facet | Massachusetts Institute of Technology. Department of Chemistry Liao, Shu-Yu Lee, Myungwoon Wang, Tuo Sergeyev, Ivan V. Hong, Mei |
| author_sort | Liao, Shu-Yu |
| collection | MIT |
| description | Although dynamic nuclear polarization (DNP) has dramatically enhanced solid-state NMR spectral sensitivities of many synthetic materials and some biological macromolecules, recent studies of membrane-protein DNP using exogenously doped paramagnetic radicals as polarizing agents have reported varied and sometimes surprisingly limited enhancement factors. This motivated us to carry out a systematic evaluation of sample preparation protocols for optimizing the sensitivity of DNP NMR spectra of membrane-bound peptides and proteins at cryogenic temperatures of ~110 K. We show that mixing the radical with the membrane by direct titration instead of centrifugation gives a significant boost to DNP enhancement. We quantify the relative sensitivity enhancement between AMUPol and TOTAPOL, two commonly used radicals, and between deuterated and protonated lipid membranes. AMUPol shows ~fourfold higher sensitivity enhancement than TOTAPOL, while deuterated lipid membrane does not give net higher sensitivity for the membrane peptides than protonated membrane. Overall, a ~100 fold enhancement between the microwave-on and microwave-off spectra can be achieved on lipid-rich membranes containing conformationally disordered peptides, and absolute sensitivity gains of 105–160 can be obtained between low-temperature DNP spectra and high-temperature non-DNP spectra. We also measured the paramagnetic relaxation enhancement of lipid signals by TOTAPOL and AMUPol, to determine the depths of these two radicals in the lipid bilayer. Our data indicate a bimodal distribution of both radicals, a surface-bound fraction and a membrane-bound fraction where the nitroxides lie at ~10 Å from the membrane surface. TOTAPOL appears to have a higher membrane-embedded fraction than AMUPol. These results should be useful for membrane-protein solid-state NMR studies under DNP conditions and provide insights into how biradicals interact with phospholipid membranes. |
| first_indexed | 2024-09-23T11:04:15Z |
| format | Article |
| id | mit-1721.1/103041 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T11:04:15Z |
| publishDate | 2016 |
| publisher | Springer Netherlands |
| record_format | dspace |
| spelling | mit-1721.1/1030412022-10-01T00:58:03Z Efficient DNP NMR of membrane proteins: sample preparation protocols, sensitivity, and radical location Liao, Shu-Yu Lee, Myungwoon Wang, Tuo Sergeyev, Ivan V. Hong, Mei Massachusetts Institute of Technology. Department of Chemistry Liao, Shu-Yu Lee, Myungwoon Wang, Tuo Hong, Mei Although dynamic nuclear polarization (DNP) has dramatically enhanced solid-state NMR spectral sensitivities of many synthetic materials and some biological macromolecules, recent studies of membrane-protein DNP using exogenously doped paramagnetic radicals as polarizing agents have reported varied and sometimes surprisingly limited enhancement factors. This motivated us to carry out a systematic evaluation of sample preparation protocols for optimizing the sensitivity of DNP NMR spectra of membrane-bound peptides and proteins at cryogenic temperatures of ~110 K. We show that mixing the radical with the membrane by direct titration instead of centrifugation gives a significant boost to DNP enhancement. We quantify the relative sensitivity enhancement between AMUPol and TOTAPOL, two commonly used radicals, and between deuterated and protonated lipid membranes. AMUPol shows ~fourfold higher sensitivity enhancement than TOTAPOL, while deuterated lipid membrane does not give net higher sensitivity for the membrane peptides than protonated membrane. Overall, a ~100 fold enhancement between the microwave-on and microwave-off spectra can be achieved on lipid-rich membranes containing conformationally disordered peptides, and absolute sensitivity gains of 105–160 can be obtained between low-temperature DNP spectra and high-temperature non-DNP spectra. We also measured the paramagnetic relaxation enhancement of lipid signals by TOTAPOL and AMUPol, to determine the depths of these two radicals in the lipid bilayer. Our data indicate a bimodal distribution of both radicals, a surface-bound fraction and a membrane-bound fraction where the nitroxides lie at ~10 Å from the membrane surface. TOTAPOL appears to have a higher membrane-embedded fraction than AMUPol. These results should be useful for membrane-protein solid-state NMR studies under DNP conditions and provide insights into how biradicals interact with phospholipid membranes. National Institutes of Health (U.S.) (NIH Grant GM088204) National Institutes of Health (U.S.) (NIH Grant GM066976) 2016-06-07T16:37:40Z 2017-03-01T16:14:48Z 2016-02 2015-12 2016-05-23T12:07:07Z Article http://purl.org/eprint/type/JournalArticle 0925-2738 1573-5001 http://hdl.handle.net/1721.1/103041 Liao, Shu Y., Myungwoon Lee, Tuo Wang, Ivan V. Sergeyev, and Mei Hong. “Efficient DNP NMR of Membrane Proteins: Sample Preparation Protocols, Sensitivity, and Radical Location.” Journal of Biomolecular NMR 64, no. 3 (February 12, 2016): 223–237. https://orcid.org/0000-0002-1801-924X https://orcid.org/0000-0003-3002-6298 https://orcid.org/0000-0001-5255-5858 https://orcid.org/0000-0002-0022-2637 en http://dx.doi.org/10.1007/s10858-016-0023-3 Journal of Biomolecular NMR Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ Springer Science+Business Media Dordrecht application/pdf Springer Netherlands Springer Netherlands |
| spellingShingle | Liao, Shu-Yu Lee, Myungwoon Wang, Tuo Sergeyev, Ivan V. Hong, Mei Efficient DNP NMR of membrane proteins: sample preparation protocols, sensitivity, and radical location |
| title | Efficient DNP NMR of membrane proteins: sample preparation protocols, sensitivity, and radical location |
| title_full | Efficient DNP NMR of membrane proteins: sample preparation protocols, sensitivity, and radical location |
| title_fullStr | Efficient DNP NMR of membrane proteins: sample preparation protocols, sensitivity, and radical location |
| title_full_unstemmed | Efficient DNP NMR of membrane proteins: sample preparation protocols, sensitivity, and radical location |
| title_short | Efficient DNP NMR of membrane proteins: sample preparation protocols, sensitivity, and radical location |
| title_sort | efficient dnp nmr of membrane proteins sample preparation protocols sensitivity and radical location |
| url | http://hdl.handle.net/1721.1/103041 https://orcid.org/0000-0002-1801-924X https://orcid.org/0000-0003-3002-6298 https://orcid.org/0000-0001-5255-5858 https://orcid.org/0000-0002-0022-2637 |
| work_keys_str_mv | AT liaoshuyu efficientdnpnmrofmembraneproteinssamplepreparationprotocolssensitivityandradicallocation AT leemyungwoon efficientdnpnmrofmembraneproteinssamplepreparationprotocolssensitivityandradicallocation AT wangtuo efficientdnpnmrofmembraneproteinssamplepreparationprotocolssensitivityandradicallocation AT sergeyevivanv efficientdnpnmrofmembraneproteinssamplepreparationprotocolssensitivityandradicallocation AT hongmei efficientdnpnmrofmembraneproteinssamplepreparationprotocolssensitivityandradicallocation |