Plate-based coupled-enzyme screens of this type are extremely valuable for identification of functional synthetic enzymes and can be applied to the evolution of a range of glycosyl transferases.

Most enzymes catalyzing the hydrolysis of terminal b-N-acetylglucosaminide linkages belong to families 3 and 20 of the glycoside hydrolases ([1,2] and the glycoside hydrolases database at URL http://afmb.cnrs-mrs. fr/CAZY/). Members of the two families greatly differ in structure, enzyme mechanism, substrate specificity, and physiologic function (for a review see [3] and references cited therein). The enzymes in family 20 are designated as N-acetylhexosaminidases (EC 3.2.1.52) because they hydrolyze b-N-acetylgalactosaminides and b-N-acetylglucosaminides, with about a four-fold greater activity on the latter ([1], and references cited therein). b-N-Acetylglucosaminidases (EC 3.2.1.52) in family 3 are much more specific for the gluco-configuration, The Gram-positive soil bacterium Cellulomonas fimi is shown to produce at least two intracellular b-N-acetylglucosaminidases, a family 20 b-N-acetylhexosaminidase (Hex20), and a novel family 3-b-N-acetylglucosaminidase ⁄ b-glucosidase (Nag3), through screening of a genomic expression library, cloning of genes and analysis of their sequences. Nag3 exhibits broad substrate specificity for substituents at the C2 position of the glycone: k cat ⁄ K m values at 25°C were 0.066 s )1 AEmm )1 and 0.076 s Abbreviations DNP-2FGlc, 2¢,4¢-dinitrophenyl 2-deoxy-2-fluoro-b-D-glucopyranoside; Dp, degree of polarization;

Osteitic changes are very common nonspecific findings on CT scans of patients with Schneiderian papillomas. Their presence as well as the degree of osteitis did not allow preoperative localization of tumor attachment.