Site-Selective Protein Immobilization by Covalent Modification of GST Fusion Proteins

The immobilization of functional proteins onto solid supports using affinity tags is an attractive approach in recent development of protein microarray technologies. Among the commonly used fusion protein tags, glutathione <i>S</i>-transferase (GST) proteins have been indispensable tools for protein–protein interaction studies and have extensive applications in recombinant protein purification and reversible protein immobilization. Here, by utilizing pyrimidine-based small-molecule probes with a sulfonyl fluoride reactive group, we report a novel and general approach for site-selective immobilization of Schistosoma japonicum GST (<i>sj</i>GST) fusion proteins through irreversible and specific covalent modification of the tyrosine-111 residue of the <i>sj</i>GST tag. As demonstrated by <i>sj</i>GST-tagged eGFP and <i>sj</i>GST-tagged kinase activity assays, this immobilization approach offers the advantages of high immobilization efficiency and excellent retention of protein structure and activity

Discovery of a Series of 2,5-Diaminopyrimidine Covalent Irreversible Inhibitors of Bruton’s Tyrosine Kinase with in Vivo Antitumor Activity

Bruton’s tyrosine kinase (Btk) is an attractive drug target for treating several B-cell lineage cancers. Ibrutinib is a first-in-class covalent irreversible Btk inhibitor and has demonstrated impressive effects in multiple clinical trials. Herein, we present a series of novel 2,5-diaminopyrimidine covalent irreversible inhibitors of Btk. Compared with ibrutinib, these inhibitors exhibited a different selectivity profile for the analyzed kinases as well as a dual-action mode of inhibition of both Btk activation and catalytic activity, which counteracts a negative regulation loop for Btk. Two compounds from this series, <b>31</b> and <b>38</b>, showed potent antiproliferative activities toward multiple B-cell lymphoma cell lines, including germinal center B-cell-like diffuse large B cell lymphoma (GCB-DLBCL) cells. In addition, compound <b>31</b> significantly prevented tumor growth in a mouse xenograft model

Selective Inhibitors of Human Neuraminidase 3

Human neuraminidases (NEU) are associated with human diseases including cancer, atherosclerosis, and diabetes. To obtain small molecule inhibitors as research tools for the study of their biological functions, we designed a library of 2-deoxy-2,3-didehydro-<i>N</i>-acetylneuraminic acid (DANA) analogues with modifications at C4 and C9 positions. This library allowed us to discover selective inhibitors targeting the human NEU3 isoenzyme. Our most selective inhibitor for NEU3 has a <i>K</i>_i of 320 ± 40 nM and a 15-fold selectivity over other human neuraminidase isoenzymes. This inhibitor blocks glycolipid processing by NEU3 in vitro. To improve their pharmacokinetic properties, various esters of the best inhibitors were synthesized and evaluated. Finally, we confirmed that our best compounds exhibited selective inhibition of NEU orthologues from murine brain

Selective Inhibitors of Human Neuraminidase 3

Human neuraminidases (NEU) are associated with human diseases including cancer, atherosclerosis, and diabetes. To obtain small molecule inhibitors as research tools for the study of their biological functions, we designed a library of 2-deoxy-2,3-didehydro-<i>N</i>-acetylneuraminic acid (DANA) analogues with modifications at C4 and C9 positions. This library allowed us to discover selective inhibitors targeting the human NEU3 isoenzyme. Our most selective inhibitor for NEU3 has a <i>K</i>_i of 320 ± 40 nM and a 15-fold selectivity over other human neuraminidase isoenzymes. This inhibitor blocks glycolipid processing by NEU3 in vitro. To improve their pharmacokinetic properties, various esters of the best inhibitors were synthesized and evaluated. Finally, we confirmed that our best compounds exhibited selective inhibition of NEU orthologues from murine brain