/?-7V-Acetylhexosaminidase (EC 3.2. 1.52) was purified from the culture nitrate of Pycnoporus cinnabarinus to homogeneity by polyaerylamide disc gel electrophoresis. The ratio of jS-GlcNAcase activity to /?-GalNAcase activity remained constant during the purification process. The molecular weight of this enzymewas estimated to be about 120,000 by gel nitration, and the isoelectric point was at about pH 5.4. The optimumpH was at 2.2 for pNPGlcNAc and around 3.7 for pNPGalNAc. The enzyme was relatively stable at acid pH range of 2-4 (for 45 hr at 5°C) and below 45°C (for lO min at pH 2.8). The enzyme hydrolysed chito-oligosaccharides, such as A^,A^-diacetylchitobiose, A^A^Af-triacetylchitotriose and AWA^TV-tetraacetylchitotetraose.
The Nim-2-adamantyloxycarbonyl (2-Adoc) group has been found to be both suitable for protection of the imidazole function of the histidine residue in peptide synthesis in terms of its stability to trifluoroacetic acid (TFA), tertiary amines and 1 -hydroxybenzotriazole (HOBt), and in its reduction of the racemization rate during the coupling reaction. Wm-2-Adoc protection has also been applied successfully to the solid-phase synthesis of thyrotropin-releasing hormone which depends on tert-butoxycarbonyl (Boc)-chemistry.
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