and 2010638002 to get D. Y. ). ligandreceptor interaction-catalyzed assimilation of small molecules around the surface of mammalian cells, this work provides useful insights to get understanding the cytotoxicity of molecular aggregates of small molecules. Although rigorous research attempts have been centered on aggregates of aberrant proteins or peptides because of their connection with neurodegenerative diseases, 1recent studies have also identified aggregates of proteins (e. g., nonpathogenic prions of cytoplasmic polyadenylation element binding protein, mitochondrial antiviral-signaling protein, or T-cell-restricted intracellular antigen 1) that have beneficial or even essential functions in cells. 2In addition, aggregates of partially unfolding -lactalbumin and oleic acid possess found application in cancer therapy. 3Similar to discoveries in study on protein aggregates, emerging evidence over the past decade from several unrelated fields (e. g., biomaterials, 4high-throughput drug screening, 5and neurodegenerative diseases6) has highlighted the significance of aggregates of small molecules in biology and medicine. With their ability to sequester enzymes or unfold proteins, 7block -amyloid formation, 6activate enzymes, 8inhibit cancer cell growth, 9or recruit mRNAs to form cell-free RNA granules, 10aggregates of small molecules constitute a new class of functional molecular entities in cellular environments. 11 Studies of such Iproniazid aggregates, however , possess frequently suffered from inconsistency and irreproducibility. 12One major cause is the lack of precise control over the production from the aggregates. Because they are hydrophobic, molecules that contact form aggregates in water usually require dissolution in an organic solvent (e. g., hexafluoroisopropanol13or dimethyl sulfoxide (DMSO)12a) before being dispersed Iproniazid in water. As a poorly controlled Iproniazid kinetic process, this type of dispersion usually results in diverse aggregates (i. e., polymorphism), even for the same molecules under the same conditions. 12aFor example, the polymorphism exhibited by A amyloids likely contributes to conflicting reports on the neurotoxic14and neuroprotective15properties. Despite this problem, there are few studies that aim to generate these aggregates in a constant and reproducible manner. 1 approach is to use an enzymatic reaction to catalyze the self-assembly of small molecules to get generating the aggregates. 16Although this approach is relatively successful and effective, the requirement of an enzyme still limits its application. Thus, we choose to explore the utilization of ligandreceptor interactions to promote the formation of aggregates of small molecules, because the formation of prion aggregates, 17in substance, can be viewed as a result of ligandreceptor conversation (here the ligand and receptor are the same protein with different conformations18). Specifically, Iproniazid we choose vancomycin (Van) because the ligand to Iproniazid promote the aggregation ofd-Ala-d-Ala derivatives (as the receptors) for three reasons: (i) The binding of Van andd-Ala-d-Ala is not only a well-established ligandreceptor interaction, 19but also capable to promote molecular self-assembly to form nanoscale aggregates (e. g., nanofibers), 20as demonstrated by Walker et al. 20b(ii) A mechanistic study by Williams et al. suggests that the binding of Van withd-Ala-d-Ala not only promotes the WNT-4 dimerization of Van andd-Ala-d-Ala, 21but also generates a conformation modify upon ligandreceptor interaction. 22(iii) Unlike the cases of other receptors (antibodies, glutathione S-transferase), it is relatively easy to modifyd-Ala-d-Ala to generate appropriate derivatives and control compounds. Thus, we designed and synthesized ad-Ala-d-Ala derivative (1) to interact with Van (Figure1A). == Physique 1 . == (A) Structures of the ligand (Van), the receptor (ad-Ala-d-Ala derivative), and the relevant regulates. (B) The ligandreceptor interaction-catalyzed molecular assimilation. Our results show that Van catalyzes the assimilation ofd-Ala-d-Ala derivatives via ligandreceptor interactions, likely via two Van binding with four molecules of1to catalyze the aggregation of1(Figure1B). The assimilation process is autocatalytic. Furthermore, cell viability tests indicate that the resulting aggregates inhibit cell growth, probably by necroptosis23of the cells. Fluorescence microscopy suggests that most of the aggregates adhere to the cell surface. The result of cell viability assessments under various incubation conditions confirms that aggregates catalyzed by ligandreceptor interactions result in cell death. Mutation ofd-Ala-d-Ala tol-Ala-l-Ala or.
