Towards in-cell structural study of light-harvesting complexes : an investigation with MAS-NMR

Light-Harvesting Complex II (LHCII) is responsible for light absorption and excitation energy transfer in plants and photosynthetic algae, while in high light it undergoes conformational changes by which it quenches excitations to prevent photodamage. The underlying molecular picture of these conformational changes has not yet been resolved. The main target of the research described in this thesis is to address the conformational dynamics of photosynthetic Light Harvesting Complex II and the role of the membrane environment. Hereto, I explored NMR-based methods that could eventually probe the molecular structure and dynamics of photosynthetic components in-vivo in functional membranes or cell systems.NWO CW-VIDI granted to Dr. Anjali Pandit, u-NMR-NL for the use of ultrahigh-field NMRSolid state NMR/Biophysical Organic Chemistr

In vivo NMR as a tool for probing molecular structure and dynamics in intact Chlamydomonas reinhardtii cells

Article / Letter to editorLeiden Institute of Chemistry;Leiden Institute of Chemistr

In vivo NMR as a tool for probing molecular structure and dynamics in intact Chlamydomonas reinhardtii cells

Article / Letter to editorLeiden Institute of Chemistry;Leiden Institute of Chemistr

In vivo NMR as a tool for probing molecular structure and dynamics in intact Chlamydomonas reinhardtii cells

Article / Letter to editorLeiden Institute of Chemistry;Leiden Institute of Chemistr

In vivo NMR as a tool for probing molecular structure and dynamics in intact Chlamydomonas reinhardtii cells

Solid state NMR/Biophysical Organic Chemistr

Towards in-cell structural study of light-harvesting complexes : an investigation with MAS-NMR

Light-Harvesting Complex II (LHCII) is responsible for light absorption and excitation energy transfer in plants and photosynthetic algae, while in high light it undergoes conformational changes by which it quenches excitations to prevent photodamage. The underlying molecular picture of these conformational changes has not yet been resolved. The main target of the research described in this thesis is to address the conformational dynamics of photosynthetic Light Harvesting Complex II and the role of the membrane environment. Hereto, I explored NMR-based methods that could eventually probe the molecular structure and dynamics of photosynthetic components in-vivo in functional membranes or cell systems.</p

In vivo NMR as a tool for probing molecular structure and dynamics in intact Chlamydomonas reinhardtii cells

Solid state NMR/Biophysical Organic Chemistr

Fractionation platform for target identification using off-line directed two-dimensional chromatography, mass spectrometry and nuclear magnetic resonance

The unambiguous identification of unknown compounds is of utmost importance in the field of metabolomics. However, current identification workflows often suffer from error-sensitive methodologies, which may lead to incorrect structure annotations of small molecules. Therefore, we have developed a comprehensive identification workflow including two highly complementary techniques, i.e. liquid chromatography (LC) combined with mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR), and used it to identify five taste-related retention time and m/z features in soy sauce. An off-line directed two-dimensional separation was performed in order to purify the features prior to the identification. Fractions collected during the first dimension separation (reversed phase low pH) were evaluated for the presence of remaining impurities next to the features of interest. Based on the separation between the feature and impurities, the most orthogonal second dimension chromatography (hydrophilic interaction chromatography or reversed phase high pH) was selected for further purification. Unknown compounds down to tens of micromolar concentrations were tentatively annotated by MS and structurally confirmed by MS and NMR. The mass (0.4-4.2 mu g) and purity of the isolated compounds were sufficient for the acquisition of one and two-dimensional NMR spectra. The use of a directed two-dimensional chromatography allowed for a fractionation that was tailored to each feature and remaining impurities. This makes the fractionation more widely applicable to different sample matrices than one-dimensional or fixed two-dimensional chromatography. Five proline-based 2,5-diketopiperazines were successfully identified in soy sauce. These cyclic dipeptides might contribute to taste by giving a bitter flavour or indirectly enhancing umami flavour. (C) 2020 The Author(s). Published by Elsevier B.V