Measurement of endo-α-mannosidase activity using a fluorescently labeled oligosaccharide derivative.

Endo-α-mannosidase, a GH99-family glycoside hydrolase, cleaves α-mannoside linkages with glucose residues. This enzyme is proposed to play a critical role in N-glycan processing for deglucosylation. To measure endo-α-mannosidase activity, we synthesized a fluorescently labeled tetrasaccharide derivative (Glcα1-3Manα1-2Manα1-2Manα1-O-C3H6-NH-Dansyl) in a stereocontrolled manner.

The region in a subunit of the Aspergillus CCAAT-binding protein similar to the HAP4p-recruiting domain of Saccharomyces cerevisiae Hap5p is not essential for transcriptional enhancement.

The CCAAT-binding complex in Aspergillus species, known as the Hap complex, consists of at least three subunits, HapB, HapC, and HapE. Each Hap subunit contains an evolutionarily conserved core domain. In this study, a series of the truncated gene, which encodes the HapE subunit of Aspergillus oryzae, was constructed to survey the regions essential for the transcriptional enhancement of fungal genes.