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A thick film of patterned heterogeneous surface is introduced, in which the surface heterogeneity arises due to a difference in the characteristics of interfacial potential. When a liquid film is coated onto such a surface, the film is unstable only on certain parts of the surface and, consequently, dewetting takes place. In the other parts, the film is stable and no dewetting takes place. This heterogeneous surface is utilized for patterning low-duty-ratio patterns, which has proved challenging for any mold-based unconventional lithographies. Only the natural forces associated with capillarity and dewetting are responsible for the patterning. As a result, defect-free and uniform patterning is possible over a large area.

Ubiquitin C-terminal hydrolase 37 (UCH37) is a deubiquitinating enzyme capable of dismantling Lys48-linked polyubiquitin chains when associated with the 26S proteasome. Upon binding to the proteasomal subunit ADRM1, UCH37 is activated for cleavage of the distal monomer in a chain, an exo-specific activity. Prior to binding with ADRM1, it is thought that UCH37 is inhibited by its own C-terminal UCHL5-like domain (ULD). Our interests lie in UCH37’s mechanism of activation by ADRM1 as well as its exo-specificity. Previously we have reported the crystal structure of T. spiralis UCH37 bound to ubiquitin vinyl methyl ester, which revealed that the ULD domain interacts with ubiquitin’s Lys48, an event we believe accounts for its exo-specificity. In order to further examine specificity and activation, we have generated a series of ULD mutants of UCH37. To probe exo-specificity, we are purifying the 19S regulatory particle of the proteasome from rabbit skeletal muscle, will reconstitute each ULD mutant within the ...

Levan is β-2,6-linked polymeric fructose and serves as reserve carbohydrate in some plants and microorganisms. Mobilization of fructose is usually mediated by enzymes such as glycoside hydrolase (GH), typically releasing a monosaccharide as a product. The enzyme levan fructotransferase (LFTase) of the GH32 family catalyzes an intramolecular fructosyl transfer reaction and results in production of cyclic difructose dianhydride, thus exhibiting a novel substrate specificity. The mechanism by which LFTase carries out these functions via the structural fold conserved in the GH32 family is unknown. Here, we report the crystal structure of LFTase from Arthrobacter ureafaciens in apo form, as well as in complexes with sucrose and levanbiose, a difructosacchride with a β-2,6-glycosidic linkage. Despite the similarity of its two-domain structure to members of the GH32 family, LFTase contains an active site that accommodates a difructosaccharide using the -1 and -2 subsites. This feature is unique among GH32 proteins and is facilitated by small side chain residues in the loop region of a catalytic β-propeller N-domain, which is conserved in the LFTase family. An additional oligosaccharide-binding site was also characterized in the β-sandwich C-domain, supporting its role in carbohydrate recognition. Together with functional analysis, our data provide a molecular basis for the catalytic mechanism of LFTase and suggest functional variations from other GH32 family proteins, notwithstanding the conserved structural elements.