Synergistic Photoenzymatic Catalysis Enables Synthesis of a-Tertiary Amino Acids Using Threonine Aldolases.

a-Tertiary amino acids are essential components of drugs and agrochemicals, yet traditional syntheses are step-intensive and provide access to a limited range of structures with varying levels of enantioselectivity. Here, we report the α-alkylation of unprotected alanine and glycine by pyridinium salts using pyridoxal (PLP)-dependent threonine aldolases with a Rose Bengal photoredox catalyst. The strategy efficiently prepares various a-tertiary amino acids in a single chemical step as a single enantiomer. UV-vis spectroscopy studies reveal a ternary interaction between the pyridinium salt, protein, and photocatalyst, which we hypothesize is responsible for localizing radical formation to the active site. This method highlights the opportunity for combining photoredox catalysts with enzymes to reveal new catalytic functions for known enzymes.

Mechanism and Dynamics of Photodecarboxylation Catalyzed by Lactate Monooxygenase.

Photoenzymes are a rare class of biocatalysts that use light to facilitate chemical reactions. Many of these catalysts utilize a flavin cofactor to absorb light, suggesting that other flavoproteins might have latent photochemical functions. Lactate monooxygenase is a flavin-dependent oxidoreductase previously reported to mediate the photodecarboxylation of carboxylates to afford alkylated flavin adducts. While this reaction holds a potential synthetic value, the mechanism and synthetic utility of this process are unknown. Here, we combine femtosecond spectroscopy, site-directed mutagenesis, and a hybrid quantum-classical computational approach to reveal the active site photochemistry and the role the active site amino acid residues play in facilitating this decarboxylation. Light-induced electron transfer from histidine to flavin was revealed, which has not been reported in other proteins. These mechanistic insights enable the development of catalytic oxidative photodecarboxylation of mandelic acid to produce benzaldehyde, a previously unknown reaction for photoenzymes. Our findings suggest that a much wider range of enzymes have the potential for photoenzymatic catalysis than has been realized to date.

Regioselective Radical Alkylation of Arenes Using Evolved Photoenzymes.

Substituted arenes are ubiquitous in molecules with medicinal functions, making their synthesis a critical consideration when designing synthetic routes. Regioselective C-H functionalization reactions are attractive for preparing alkylated arenes; however, the selectivity of existing methods is modest and primarily governed by the substrate's electronic properties. Here, we demonstrate a biocatalyst-controlled method for the regioselective alkylation of electron-rich and electron-deficient heteroarenes. Starting from an unselective "ene"-reductase (ERED) (GluER-T36A), we evolved a variant that selectively alkylates the C4 position of indole, an elusive position using prior technologies. Mechanistic studies across the evolutionary series indicate that changes to the protein active site alter the electronic character of the charge transfer (CT) complex responsible for radical formation. This resulted in a variant with a significant degree of ground-state CT in the CT complex. Mechanistic studies on a C2-selective ERED suggest that the evolution of GluER-T36A helps disfavor a competing mechanistic pathway. Additional protein engineering campaigns were carried out for a C8-selective quinoline alkylation. This study highlights the opportunity to use enzymes for regioselective radical reactions, where small molecule catalysts struggle to alter selectivity.

Photobiocatalytic Strategies for Organic Synthesis.

Biocatalysis has revolutionized chemical synthesis, providing sustainable methods for preparing various organic molecules. In enzyme-mediated organic synthesis, most reactions involve molecules operating from their ground states. Over the past 25 years, there has been an increased interest in enzymatic processes that utilize electronically excited states accessed through photoexcitation. These photobiocatalytic processes involve a diverse array of reaction mechanisms that are complementary to one another. This comprehensive review will describe the state-of-the-art strategies in photobiocatalysis for organic synthesis until December 2022. Apart from reviewing the relevant literature, a central goal of this review is to delineate the mechanistic differences between the general strategies employed in the field. We will organize this review based on the relationship between the photochemical step and the enzymatic transformations. The review will include mechanistic studies, substrate scopes, and protein optimization strategies. By clearly defining mechanistically-distinct strategies in photobiocatalytic chemistry, we hope to illuminate future synthetic opportunities in the area.

Regioselective Radical Alkylation of Arenes Using Evolved Photoenzymes.

Substituted arenes are ubiquitous in molecules with medicinal functions, making their synthesis a critical consideration when designing synthetic routes. 1,2 Regioselective C-H functionalization reactions are attractive for preparing alkylated arenes, 3-5 however, the selectivity of existing methods is modest and primarily governed by substrate electronic properties. 6,7 Here, we demonstrate a biocatalyst-controlled method for the regioselective alkylation of electron-rich and electron-deficient heteroarenes. Starting from an unselective 'ene'-reductase (ERED) (GluER-T36A), we evolved a variant that selectively alkylates the C4 position of indole, an elusive position using prior technologies. Mechanistic studies across the evolutionary series indicate that changes to the protein active site alter the electronic character of the charge transfer (CT) complex responsible for radical formation. This resulted in a variant with a significant degree of ground state change transfer in the CT complex. Mechanistic studies on a C2 selective ERED suggest that the evolution of GluER-T36A helps disfavor a competing mechanistic pathway. Additional protein engineering campaigns were carried out for a C8 selective quinoline alkylation. This study highlights the opportunity to use enzymes for regioselective reactions where small molecule catalysts struggle to alter selectivity.

Engineered red blood cells (activating antigen carriers) drive potent T cell responses and tumor regression in mice.

Activation of T cell responses is essential for effective tumor clearance; however, inducing targeted, potent antigen presentation to stimulate T cell responses remains challenging. We generated Activating Antigen Carriers (AACs) by engineering red blood cells (RBCs) to encapsulate relevant tumor antigens and the adjuvant polyinosinic-polycytidylic acid (poly I:C), for use as a tumor-specific cancer vaccine. The processing method and conditions used to create the AACs promote phosphatidylserine exposure on RBCs and thus harness the natural process of aged RBC clearance to enable targeting of the AACs to endogenous professional antigen presenting cells (APCs) without the use of chemicals or viral vectors. AAC uptake, antigen processing, and presentation by APCs drive antigen-specific activation of T cells, both in mouse in vivo and human in vitro systems, promoting polyfunctionality of CD8+ T cells and, in a tumor model, driving high levels of antigen-specific CD8+ T cell infiltration and tumor killing. The efficacy of AAC therapy was further enhanced by combination with the chemotherapeutic agent Cisplatin. In summary, these findings support AACs as a potential vector-free immunotherapy strategy to enable potent antigen presentation and T cell stimulation by endogenous APCs with broad therapeutic potential.

Photoenzymatic Catalysis in a New Light: Gluconobacter "Ene"-Reductase Conjugates Possessing High-Energy Reactivity with Tunable Low-Energy Excitation.

Non-natural light-driven enzymatic reactivity was recently developed to perform the highly stereoselective reactions required for pharmaceutical synthesis. However, photoenzymes require high-intensity light to function because of the poor absorption properties of their photoactive intermediates. Inspired by the modular architecture of photosynthesis, we designed a conjugate composed of a covalently linked photoenzyme and a light antenna to separate light capture from catalysis. Spectroscopic characterization of the conjugate showed the presence of efficient energy transfer from the light-harvesting components to the photoenzyme. In the presence of energy transfer, a ∼4-fold increase in product yield was observed for intramolecular hydroalkylation of alkenes, and reactivity was enabled for intermolecular hydroalkylation of alkenes. These improvements establish the power of incorporating nature's design into non-natural photoenzymatic catalysis.

Quaternary Charge-Transfer Complex Enables Photoenzymatic Intermolecular Hydroalkylation of Olefins.

Intermolecular C-C bond-forming reactions are underdeveloped transformations in the field of biocatalysis. Here we report a photoenzymatic intermolecular hydroalkylation of olefins catalyzed by flavin-dependent 'ene'-reductases. Radical initiation occurs via photoexcitation of a rare high-order enzyme-templated charge-transfer complex that forms between an alkene, α-chloroamide, and flavin hydroquinone. This unique mechanism ensures that radical formation only occurs when both substrates are present within the protein active site. This active site can control the radical terminating hydrogen atom transfer, enabling the synthesis of enantioenriched γ-stereogenic amides. This work highlights the potential for photoenzymatic catalysis to enable new biocatalytic transformations via previously unknown electron transfer mechanisms.

[Nurse's role in primary care for people with common mental disorders]. / Le rôle des infirmières dans les services de première ligne face aux personnes souffrant d'un trouble mental courant.

The prevalence of common mental disorders (CMD) increases both in Quebec and in the world. Governments, researchers and clinicians are in search of the best practices to improve the services offered to clients with CMD. The data suggest that these services should be primarily offered in primary care, but their current organization in Quebec does not adequately address the needs of people with CMD as well as those of their relatives. Over the next few years, different types of nurses will have an expanded role in primary care and will represent a larger portion of the workforce at this level, potentially improving access to services. Nurses and other clinicians are not always aware of the role of nurses in mental health and their contribution to all phases of the continuum of care. Interprofessional collaboration is fundamental to improving mental primary care services and is based on a fair understanding of roles among all members of a team. The objectives of this article are to: 1) describe best practices in primary care for interprofessional collaboration in mental health; 2) discuss the roles of nurses in CMD; and (3) to present avenues of intervention to extend these roles. A conceptualization of nursing roles well integrated into an multiprofessional primary care practice in mental health is presented in this article.

Reversible Product Release and Recapture by a Fungal Polyketide Synthase Using a Carnitine Acyltransferase Domain.

Fungal polyketides have significant biological activities, yet the biosynthesis by highly reducing polyketide synthases (HRPKSs) remains enigmatic. An uncharacterized group of HRPKSs was found to contain a C-terminal domain with significant homology to carnitine O-acyltransferase (cAT). Characterization of one such HRPKS (Tv6-931) from Trichoderma virens showed that the cAT domain is capable of esterifying the polyketide product with polyalcohol nucleophiles. This process is readily reversible, as confirmed through the holo ACP-dependent transesterification of the released product. The methyltransferase (MT) domain of Tv6-931 can perform two consecutive α-methylation steps on the last ß-keto intermediate to yield an α,α-gem-dimethyl product, a new programing feature among HRPKSs. Recapturing of the released product by cAT domain is suggested to facilitate complete gem-dimethylation by the MT.

[Advanced nursing practice: a must for the quality of care and mental health services]. / La pratique infirmière avancée: un choix qui s'impose pour la qualité des soins et services en santé mentale.

New professional legislation and reorganization of mental health services have had a significant influence on mental health nursing practice. Many nurses have demonstrated clinical leadership and have been able to adapt their services to the needs of the population specially in the primary health care setting. However, many believe that the role of nurses is not sufficiently known and optimally utilized in mental health services. In this article we take a critical look at the mental health nursing practice in Quebec and at the essential requirements for its development. This review aims to: 1) describe current trends in the changing roles and the modernization of mental health nursing practice in Quebec, 2) provide an overview of the development of advanced nursing practice and its impact on the quality of mental health services; 3) clarify the concept of advanced nursing practice and position its development in Quebec and 4) propose various strategies for optimizing the role of nurses and their complementarity with other professionals providing mental health services. This review presents innovative practices developed by nurses in the context of the restructuring of mental health services. For example, new nursing roles have been developed to improve the collaboration with general practitioners groups in primary care settings and facilitate the evaluation and monitoring of patient presenting medical and psychological problems. Another interesting innovation was set up by nurses in developing a new service to allow timely access to integrated care for patients with substance abuse and mental health problems. The various testimonies reported in this article illustrate the potential contribution of these nursing innovations in improving the mental health services in Quebec. Also, in few countries, the reform of mental health services has been a good time to recognize this potential. Thus, some countries have repositioned the role of mental health nurses and supported the development of new models of advanced practice in mental health. These developments have been particularly significant in the United States and Australia. In United States, during the 1990s, at least four models of advanced practice in mental health nursing have been developed leading to wide variations in the roles, education, job titles, scope of practice and legal authorizations. Consequently, a consensus model of uniform standards of practice, accreditation and education has been proposed. This LACE model (Licensure, Accreditation, Certification, Education) will be in effect in 2015. Australia has adopted a more systematic approach, unified and progressive to facilitate the development of advanced mental health nursing practice. Australia who, through their many publications, retains more attention since a clear definition of the role of the nurse practitioner in mental health and a legal framework has been adopted at the national level. The Australian experience and the finding from studies suggest that mental health nurse practitioners and nurses who are specialized in mental health have the potential to make a significant contribution to enhancing access to and quality of mental health care through flexible an innovative approaches. So there are more and more evidence and indications that Quebec should invest in enhancing the skills of mental health nurses through the development of advanced nursing practice and integration of this new model in primary care. In addition, researches, funded by the Canadian Services Research Foundation (CHSRF, 2010), shows that the contribution of advanced nursing practice has never been stronger and there is a broad consensus to its value for the Canadian health care system (Dicenso.et Lukosius-Briant, 2010). The implementation of advanced practice nursing role in mental health is part of best practices required to improve care and mental health services and should be taken into account in future Action Plan 2014-2020.