The authors have previously synthesized a novel boronate affinity ligand, catechol [2-(diethylamino)carbonyl-4-bromomethyl]phenylboronate. When this ligand was coupled to cellulose beads, it bound horseradish peroxidase (HRP), a glycoprotein, at pH 7.0. In comparison, commercial m-aminophenylboronic acid-agarose did not bind HRP below pH 8.0. HRP was immobilized in an oriented and reversible fashion using this gel. The immobilized enzyme retained 90.12 per cent of its original activity, probably due to its attachment via the carbohydrate moiety of the enzyme. After repeated use, the activity remaining on the new gel was twice as high as that on conventional m-aminophenylboronic acid-agarose. The column was regenerated easily by washing with dilute acid because of reversibility of the boronate glycol bond.

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The chemoenzymatic preparation of a nine-member Ugi condensation library is described. The carboxylic acid and amine precursors are based on 3-hydroxybutyrate and 4-amino-1-butanol, respectively, and have been acylated selectively using a variety of acyl donors catalyzed by porcine pancreatic lipase. The enzyme is selective for the hydroxyl functionalities on both precursors, thereby yielding 3-acyl-butyric acid and 4-amino-1-acyl compounds. These enzymatically generated derivatives were then subjected to a four-component Ugi condensation reaction in the presence of acetaldehyde and methyl isocyanoacetate. Isolated yields of the alpha-(acylamino)amide Ugi products ranged from 72-95%. The inherent chemoselectivity of enzymatic catalysis may play an increasingly important role in expanding the structural diversity that can be achieved by chemical multicomponent condensation reactions.

Most unsymmetric quadrilateral elements have demonstrated a high tolerance to mesh distortion in pure bending problems involving coarse meshes. However, they have difficulty achieving acceptable results in shearing-dominated problems, and the element's performance is affected by the degree of mesh distortion.In this paper, two 8-node quadrilateral elements are developed by introducing two different incompatible modes into the unsymmetric formulation. The unsymmetric framework with two different sets of interpolation functions for displacement fields provides the basis for the immunity property. The incompatible displacement mode and the enhanced assumed strain guarantee the completeness of the displacement field interpolation polynomials, and the satisfaction of L 2 -orthogonality condition ensures the accuracy of the simulations.The resulting elements, respectively, denoted as UQ10 and UQ10/E4, can provide exact solutions for both pure and linear bending problems and exhibit excellent insensitivity in shear-dominated tests. Furthermore, they are invariant, rapidly converging, and free of various locking problems.