35 従属栄養期のトウモロコシにおけるN-Acetylhexosaminidaseの精製及び性状解析

抄録

Occurrence of N-acetylhexosaminidase was found in young maize seedlings. Most of activity was localized in the embryo before germination. After germination, the strongest activity was detected in scutellum, while the activity was hardly detectable in roots and shoots. The high activity in scutellum was sustained until 80 hours after germination. When N-acetylchitobiose [(GIcNAc)_2] was used as substrate, this enzyme showed a pH optimum at pH 4.5 and a temperature optimum at 55℃. The native molecular mass and isoelectric point (pI) were determined as 44 kDa and 6.45, respectively. Apparent K_m value for (GlcNAc)_2was estimated to be 0.1.24 mM, while the value for p-nitrophenyl-N-acetylglucoside was 0.400 mM.