In mammals, ␣-linked GlcNAc is primarily found in heparan sulfate/heparin and gastric gland mucous cell type mucin. ␣-N-Acetylglucosaminidases (␣GNases) belonging to glycoside hydrolase family 89 are widely distributed from bacteria to higher eukaryotes. Human lysosomal ␣GNase is well known to degrade heparin and heparan sulfate. Here, we reveal the substrate specificity of ␣GNase (AgnC) from Clostridium perfringens strain 13, a bacterial homolog of human ␣GNase, by chemically synthesizing a series of disaccharide substrates containing ␣-linked GlcNAc. AgnC was found to release GlcNAc from GlcNAc␣1,4Gal␤1pMP and GlcNAc␣1pNP substrates (where pMP and pNP represent p-methoxyphenyl and p-nitrophenyl, respectively). AgnC also released GlcNAc from porcine gastric mucin and cell surface mucin. Because AgnC showed no activity against any of the GlcNAc␣1,2Gal␤1pMP, GlcNAc␣1,3Gal␤1pMP, GlcNAc␣1,6Gal␤1pMP, and GlcNAc␣1,4GlcA␤1pMP substrates, this enzyme may represent a specific glycosidase required for degrading ␣-GlcNAccapped O-glycans of the class III mucin secreted from the stomach and duodenum. Deletion of the C-terminal region containing several carbohydrate-binding module 32 (CBM32) domains significantly reduced the activity for porcine gastric mucin; however, activity against GlcNAc␣1,4Gal␤1pMP was markedly enhanced. Dot blot and ELISA analyses revealed that the deletion construct containing the C-terminal CBM-C2 to CBM-C6 domains binds strongly to porcine gastric mucin. Consequently, tandem CBM32 domains located near the C terminus of AgnC should function by increasing the affinity for branched or clustered ␣-GlcNAc-containing glycans. The agnC gene-disrupted strain showed significantly reduced growth on the class III mucin-containing medium compared with the wild type strain, suggesting that AgnC might have an important role in dominant growth in intestines.

Racemic 6,6′-dimethylbiphenyl-2,2′-dicarboxylic acid (1) could be conveniently synthesized and efficiently resolved by the recrystallization of the brucine salts in satisfactory yields. Each enantiomer, thus obtained, was confirmed to be optically pure from a high-performance liquid chromatographic (HPLC) analysis on an optically active column.

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Three kinds of beta-cyclodextrin derivatives conjugated with glucose moieties, which were expected as models for a drug carrier targeting the drug delivery systems, were designed and synthesized from beta-cyclodextrin and the natural product, 4-hydroxyphenyl-beta-D-glucopyranoside called arbutin. Arbutin was used because it had a phenyl group with a hydroxyl function which could be used to link the glucose moiety to beta-cyclodextrin. The evaluations of these conjugates as the drug-carrying molecules were done by investigating the molecular interactions with the carbohydrate-binding Concanavalin A (Con A) lectin and the anticancer agent, doxorubicin (DXR), using an SPR optical biosensor. The association constants of the conjugates with immobilized Con A were 2.0 x 10(3) approximately 8.8 x 10(3) M(-1). The result showed that the Con A bound to the glucose moieties from arbutin in the conjugates with prospective association constants. The inclusion associations of the conjugates with immobilized DXR reached 2.2 x 10(5) approximately 1.4 x 10(8) M(-1). The extremely high inclusion associations for DXR suggested their potential abilities as drug-carrying molecules for carrying DXR. The NMR analyses indicated that the phenyl group of the conjugates greatly served to increase the inclusion associations for DXR. In their DXR inclusion complexes, the formation of the stacking complexes by the pi;-pi interactions between the phenyl groups and the included DXR also enhanced their inclusion abilities for DXR.

The catalytic enantioselective reaction of α-phenylthioacetonitriles with imines has been developed. The reaction of various imines proceeds in good yields and diastereo- and enantioselectivities in the presence of chiral bis(imidazoline)-palladium catalysts. The obtained products can be converted into β-aminonitrile or β-aminoamide compounds without loss of enantiopurity.