Abstract:The solid-state photo-chemically induced dynamic nuclear polarization (photo-CIDNP) effect generates non-Boltzmann nuclear spin magnetization, referred to as hyperpolarization, allowing for high gain of sensitivity in nuclear magnetic resonance (NMR). Well known to occur in photosynthetic reaction centers, the effect was also observed in a light-oxygen-voltage (LOV) domain of the blue-light receptor phototropin, in which the functional cysteine was removed to prevent photo-chemical reactions with the cofactor,… Show more
“…The discovery of the solid-state photo-CIDNP effect in flavoproteins opened a new world of experiments, in particular because in these systems the electron donor is an aromatic amino acid which, using side-directed mutagenesis, can be shifted to other positions in the protein, varying distance, orientation and strength of couplings (Figure ). , Presently, understanding of the photo-CIDNP mechanism in flavoproteins is required. It must be distinguished from that in photosynthetic RCs, in which the RP is born in a singlet state, while in flavoproteins the electron transfer is initiated by the triplet state of the flavin cofactor.…”
Magnetic resonance techniques are successfully utilized in a broad range of scientific disciplines and in various practical applications, with medical magnetic resonance imaging being the most widely known example. Currently, both fundamental and applied magnetic resonance are enjoying a major boost owing to the rapidly developing field of spin hyperpolarization. Hyperpolarization techniques are able to enhance signal intensities in magnetic resonance by several orders of magnitude, and thus to largely overcome its major disadvantage of relatively low sensitivity. This provides new impetus for existing applications of magnetic resonance and opens the gates to exciting new possibilities. In this review, we provide a unified picture of the many methods and techniques that fall under the umbrella term "hyperpolarization" but are currently seldom perceived as integral parts of the same field. Specifically, before delving into the individual techniques, we provide a detailed analysis of the underlying principles of spin hyperpolarization. We attempt to uncover and classify the origins of hyperpolarization, to establish its sources and the specific mechanisms that enable the flow of polarization from a source to the target spins. We then give a more detailed analysis of individual hyperpolarization techniques: the mechanisms by which they work, fundamental and technical requirements, characteristic applications, unresolved issues, and possible future directions. We are seeing a continuous growth of activity in the field of spin hyperpolarization, and we expect the field to flourish as new and improved hyperpolarization techniques are implemented. Some key areas for development are in prolonging polarization lifetimes, making hyperpolarization techniques more generally applicable to chemical/biological systems, reducing the technical and equipment requirements, and creating more efficient excitation and detection schemes. We hope this review will facilitate the sharing of knowledge between subfields within the broad topic of hyperpolarization, to help overcome existing challenges in magnetic resonance and enable novel applications.
“…The discovery of the solid-state photo-CIDNP effect in flavoproteins opened a new world of experiments, in particular because in these systems the electron donor is an aromatic amino acid which, using side-directed mutagenesis, can be shifted to other positions in the protein, varying distance, orientation and strength of couplings (Figure ). , Presently, understanding of the photo-CIDNP mechanism in flavoproteins is required. It must be distinguished from that in photosynthetic RCs, in which the RP is born in a singlet state, while in flavoproteins the electron transfer is initiated by the triplet state of the flavin cofactor.…”
Magnetic resonance techniques are successfully utilized in a broad range of scientific disciplines and in various practical applications, with medical magnetic resonance imaging being the most widely known example. Currently, both fundamental and applied magnetic resonance are enjoying a major boost owing to the rapidly developing field of spin hyperpolarization. Hyperpolarization techniques are able to enhance signal intensities in magnetic resonance by several orders of magnitude, and thus to largely overcome its major disadvantage of relatively low sensitivity. This provides new impetus for existing applications of magnetic resonance and opens the gates to exciting new possibilities. In this review, we provide a unified picture of the many methods and techniques that fall under the umbrella term "hyperpolarization" but are currently seldom perceived as integral parts of the same field. Specifically, before delving into the individual techniques, we provide a detailed analysis of the underlying principles of spin hyperpolarization. We attempt to uncover and classify the origins of hyperpolarization, to establish its sources and the specific mechanisms that enable the flow of polarization from a source to the target spins. We then give a more detailed analysis of individual hyperpolarization techniques: the mechanisms by which they work, fundamental and technical requirements, characteristic applications, unresolved issues, and possible future directions. We are seeing a continuous growth of activity in the field of spin hyperpolarization, and we expect the field to flourish as new and improved hyperpolarization techniques are implemented. Some key areas for development are in prolonging polarization lifetimes, making hyperpolarization techniques more generally applicable to chemical/biological systems, reducing the technical and equipment requirements, and creating more efficient excitation and detection schemes. We hope this review will facilitate the sharing of knowledge between subfields within the broad topic of hyperpolarization, to help overcome existing challenges in magnetic resonance and enable novel applications.
“…Furthermore, flavoproteins allow properties of the SCRP such as the distance between the radicals and their orientations (Fig. 3 ) to be customized, opening again “new categories of experiments” [ 98 ]. Fig.…”
Section: Studies On Flavoproteinsmentioning
confidence: 99%
“…The differences observed between the two mutants having a distance of ~ 11 Å suggest, in addition to a distance dependence, an orientation dependence of the donor and acceptor units. Interestingly, at longer distance (~ 17 Å) and in the cysteine-less mutant without tryptophan, same patterns occur implying that other amino acids, assumably tyrosines, take over the role of the electron donor [ 98 ] …”
Photo-CIDNP (photo-chemically induced dynamic nuclear polarization) refers to nuclear polarization created by the spin-chemical evolution of spin-correlated radical pairs (SCRPs). This phenomenon occurs in gases, liquids and solids. Based on the solid-state photo-CIDNP effect observed under magic-angle spinning (MAS), photo-CIDNP MAS NMR has been developed as analytical method. Here we report the origin, the theory and the state of the art of this method.
“…Inzwischen gibt es auch einige Beispiele von Flavoproteinen, die den Vorteil haben, mit Mutationen den gewünschten Bedingungen angepasst werden zu können. 71) Zudem wurde das Konzept von Level-Crossings und Level-Anti-Crossings auf photo-CIDNP übertragen. 72) Dieses auch in der Photochemie etwa durch Turro verbreitete Konzept geht auf die Arbeit von von Neumann und Wigner aus dem Jahr 1929 zurück, die Thermodynamik und Quantentheorie verbindet.…”
Section: Pharmazeutische Und Biologische Lösungs-nmrunclassified
Der gesellschaftliche Diskurs ist derzeit geprägt durch Themen wie Gesundheit und Nachhaltigkeit. Damit einher geht der Bedarf, Strukturen und Eigenschaften von Proteinen, RNA, Wirkstoffen und Zellen besser zu verstehen, ebenso wie Materialien, Rohstofftransformation, Energiespeicherung und Produktionsprozesse. Fortschritte in Technik und Methodik der NMR tragen dazu bei.
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