Multivalency represents an appealing option to modulate selectivity in enzyme inhibition and transform moderate glycosidase inhibitors into highly potent ones. The rational design of multivalent inhibitors is however challenging because global affinity enhancement relies on several interconnected local mechanistic events, whose relative impact is unknown. So far, the largest multivalent effects ever reported for a non-polymeric glycosidase inhibitor have been obtained with cyclopeptoid-based inhibitors of Jack bean α-mannosidase (JBα-man). Here, we report a structure-activity relationship (SAR) study based on the top-down deconstruction of best-in-class multivalent inhibitors. This approach provides a valuable tool to understand the complex interdependent mechanisms underpinning the inhibitory multivalent effect. Combining SAR experiments, binding stoichiometry assessments, thermodynamic modelling and atomistic simulations allowed us to establish the significant contribution of statistical rebinding mechanisms and the importance of several key parameters, including inhitope accessibility, topological restrictions, and electrostatic interactions. Our findings indicate that strong chelate-binding, resulting from the formation of a cross-linked complex between a multivalent inhibitor and two dimeric JBα-man molecules, is not a sufficient condition to reach high levels of affinity enhancements. The deconstruction approach thus offers unique opportunities to better understand multivalent binding and provides important guidelines for the design of potent and selective multiheaded inhibitors.
Abstract Invited for the cover of this issue are the groups of Giorgio Della Sala at the Università degli Studi di Salerno and Luigi Cavallo at the King Abdullah University of Science and Technology. The image depicts the transition state involved in the crown ether catalyzed arylogous Michael reaction of phthalides. Read the full text of the article at 10.1002/chem.201900168 .
Abstract Multivalency represents a powerful approach to increase the inhibition potency of moderate glycosidase inhibitors. Regarding the key role of catalytic glycoside hydrolysis in biology, understanding the molecular mechanisms and origin of the multivalent inhibitory effect is of great interest and presents a fascinating playground for theoretical studies. Our teams have recently dissected key processes of multivalent glycosidase inhibition through the use of different neoglycoclusters based on deoxynojirimycin (DNJ) inhitopes and a cyclopeptoid scaffold. This companion article details the theoretical aspects of this former study. A thermodynamic model is developed and validated, compared to literature, and extended to account for particularities of the charged DNJ inhitopes.
Head-to-tail cyclization of linear oligoamides containing 4-benzylaminomethyl-1H-1,2,3-triazol-1-yl acetic acid monomers afforded a novel class of "extended macrocyclic peptoids". The identification of the conformation in solution for a cyclodimer and the X-ray crystal structure of a cyclic tetraamide are reported.
The synthesis of enantiopure organic compounds is a key issue for several applications in pharmacology, food chemistry, agricultural chemistry, perfumery, materials science and other industrial sectors. Nowadays, asymmetric catalysis is undoubtedly the most important tool to achieve this goal. This technology, in fact, enables the production of large amounts of enantiomerically enriched compounds, employing relatively small quantities of chiral enantiopure catalysts, which is exactly what is accomplished by enzymes in nature. Since the pioneering works of Noyori, Knowles and Sharpless, which later earned them the Nobel Prize in Chemistry, asymmetric catalysis has experienced a rapid and relentless development in the last fifty years. The tremendous expansion of enantioselective transformations, the design of novel and more efficient organometallic and organic catalysts, the development of sophisticated bioreactors and cell factories, are just some of the elements responsible for such growth. However, new challenges of asymmetric catalysis are devoted to enhancing the process's sustainability, by the introduction of recyclable and low-cost catalysts, and the use of renewable starting materials and energy source. This book provides an overview of some of these development directions and comprises a collection of review papers and a research article authored by renowned researchers actively involved in this field. The topics covered by the review papers are photoredox-catalyzed reactions of imines, asymmetric catalytic electrosynthesis, cooperative catalysis of chiral N-heterocyclic carbenes and Lewis acid, and asymmetric ring-opening reactions of epoxides catalyzed by metal–salen complexes. The research article presents a proline-catalyzed aldol reaction in water–methanol solvent mixture.
