In vivo targeting by glycan pattern recognitionIn nature, one of the major components that drives cell-to-cell interactions is glycan recognition with lecitns. Most types of malignant and diseased cells compared to healthy cells have altered their glycan patterns, hence this represents a potential targeting mechanism. Individually, lectin-glycan interactions are poor (Kd in the mM range), such that their one-to-one interactions have little biological selectivity. However, due to the enormous presence of lectin isoforms, especially in cancer cells, the combined interactions of clustered sugars (i.e., homogeneous vs. heterogeneous) allows for strong and selective cell binding in nature; we refer to the phenomena here as “glycan pattern recognition”. One issue with conjugating large biomolecules is that conventional protein ligation techniques often suffer from low yields. We have therefore developed the RIKEN click reaction (aza-electric cyclization of 1-azatriene produced from unsaturated aldehyde probe and lysines)1) to efficiently conjugate various N-glycan molecules (asparagine-linked glycan) to proteins, especially to human serum albumin, in a short time under extremely mild conditions. Using this methodology, we synthesized “structurally well-defined” homogeneous (single glycan type) and heterogeneous (combination of glycan types) glycocluster environments on albumin surfaces2,3). Subsequent studies using these glycoalbumins then allowed a deeper investigation on “pattern recognition mechanisms” for the effects of multivalent glycan interactions to influence trafficking pathways. Results were able to identify several glycoclusters This report is to depict the steps taken by our group for the development of glycosylated artificial metalloenzymes (GArMs) that we have used to develop therapeutic in vivo synthetic chemistry. To achieve this goal, we have had to combine technologies developed over the course of a decade that range from protein conjugation methodologies, identification of glycan-dependent targeting, development of functional biocatalysis and the biocompatible reactions. As a result, we have begun to reveal the framework for GArM complexes and their potential towards creating novel biotechnological tools and therapeutic applications.that could rapidly (within an hour) target various organs and specific tumors, as well as alter excretion pathways.2,3) Overall, the use of glycan pattern recognition for organs or cancer cells targeting represents a novel and promising strategy for the development of diagnostic, prophylactic, and therapeutic agents for various diseases. Moreover, the use of glycan targeting would have significant advantages over current techniques (e.g., antibody), such as shorter accumulation times and lower immunogenicity.Our first attempt at developing in vivo GArMs came during a study to determine whether specific tissues of mice could be targeted for in vivo labeling (Figure A-I)6). In this work, glycosylated ArM-Au-1 with the intent to label targeted cells in vivo with propargyl ester-based probes. As depicted in Figure A-II, mice were first intravenously injected through the tail vein with a ArM-Au-1. Then, a near infrared fluorescent propargyl ester (Cy7.5-PE) was injected. As shown in the In vivo metal-catalyzed reactions for therapeutic applicationGiven our interest in both glycan targeting and biocatalysis, a natural course of action eventually led to combining both aspects of targeting glycoproteins and ArMs to establish the concept of glycosylated artificial metalloenzymes (GArMs). The ultimate goal of this endeavor will be to eventually establish effective and biocompatible therapeutic ArMs, which can then be conferred with organ/tumor targeting properties by simply decorating the protein scaffold with an appropriate glycan assembly. We serendipitously discovered that when the various transition metal catalysts were introduced into the hydrophobic pocket of glycosylated albumin through the coumarin ligand, the metal catalysts could be protected under biological conditions4,5). Namely, our GArMs can catalyze the various organic transformations even in the presence of 20 mM of glutathiones! To our knowledge, this technology could constitute the 1st example for the in vivo metal-catalyzed chemistry from view points of applicability, generality and safety to be used for clinical applications.109Therapeutic in vivo synthetic chemistry by glycosylated artificial metalloenzymeKatsunori Tanaka1Tsung-che Chang and 1,2Katsunori Tanaka1Biofunctional Synthetic Chemistry Laboratory, RIKEN Cluster for pioneering research, 2Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of technology
元のページ ../index.html#109