A novel series of piperidine-linked amino-triazine derivatives were designed, synthesized and evaluated for in vitro anti-HIV activity as non-nucleoside reverse transcriptase inhibitors on the basis of our previous work. Screening results indicated that most compounds showed excellent activity against wild-type HIV-1 with EC(50) values in low nanomolar concentration range (especially compound 6b3, EC(50) = 4.61 nM, SI = 5945) and high activity against K103N/Y181C resistant mutant strain of HIV-1 with EC(50) values in low micromolar concentration range. In addition, preliminary structure-activity relationship and molecular modeling of these new analogs were detailed in this manuscript.

O-Mannose glycans, a family of highly heterogeneous complex glycans account up to 30% of total O-glycans in brain. Previous synthesis and functional studies only focused on the Core M3 O-mannose glycans of α-dystroglycan which are a causative factor for various muscular diseases. In this study, a highly efficient chemoenzymatic strategy was developed that enabled the first collective synthesis of 63 Core M1 and Core M2 O-mannose glycans. This chemoenzymatic strategy features the gram-scale chemical synthesis of 5 judiciously designed core structures, and the diversity-oriented modification of the core structures with 3 enzyme modules to provide 58 complex O-mannose glycans in a linear sequence that does not exceed 4 steps. Of note, 55 of these O-mannose glycans are synthesized for the first time. Using the printed O-mannose glycan array, the human brain protein CD33, a key factor in the modulation of Alzheimer’s disease was identified as strongly binding to sialylated Core M1 and Core M2.

The diversity-oriented chemoenzymatic synthesis of α-dystroglycan (α-DG) core M1 O-mannose glycans has been achieved via a three-step sequential one-pot multienzyme (OPME) glycosylation of a chemically prepared disaccharyl serine intermediate. The high flexibility and efficiency of this chemoenzymatic strategy was demonstrated for the synthesis of three more complex core M1 O-mannose glycans for the first time along with three previously reported core M1 structures.

Scheme 4. a) The three enzyme modules for enzymatic diversification. b) Enzymatic assemblyo fcore M1 O-mannose glycans 16-21 from 1. c) Enzymatic assembly of C6-branched core M1 O-mannose glycan isomers 22-27 from 2.d)Enzymatic assemblyo fsymmetricalc ore M2 O-mannose glycans 28-33 from 3.

Avibacterium paragallinarum is a Gram-negative bacterium that causes infectious coryza in chicken. It was reported that the capsule polysaccharides extracted from Av. paragallinarum genotype A contained chondroitin. Chondroitin synthase of Av. paragallinarum (ApCS) encoded by one gene within the presumed capsule biosynthesis gene cluster exhibited considerable homology to identified bacterial chondroitin synthases. Herein, we report the identification and characterization of ApCS. This enzyme indeed displays chondroitin synthase activity involved in the biosynthesis of the capsule. ApCS is a bifunctional protein catalyzing the elongation of the chondroitin chain by alternatively transferring the glucuronic acid (GlcA) and N-acetyl-D-galactosamine (GalNAc) residues from their nucleotide forms to the non-reducing ends of the saccharide chains. GlcA with a para-nitrophenyl group (pNP) could serve as the acceptor for ApCS; this enzyme shows a stringent donor tolerance when the acceptor is as small as this monosaccharide. Then, UDP-GalNAc and GlcA-pNP were injected sequentially through the chip-immobilized chondroitin synthases, and the surface plasmon resonance data demonstrated that the up-regulated extent caused by the binding of the donor is one possibly essential factor in successful polymerization reaction. This conclusion will, therefore, enhance the understanding of the mode of action of glycosyltransferase. Surprisingly, high activity at near-zero temperature as well as weak temperature dependence of this novel bacterial chondroitin synthase indicate that ApCS was a cold-active enzyme. From all accounts, ApCS becomes the fourth known bacterial chondroitin synthase, and the potential applications in artificial chondroitin sulfate and glycosaminoglycan synthetic approaches make it an attractive glycosyltransferase for further investigation.