XXII. BIOCHEMICKÝ ZJAZD - Jesseniova lekárska fakulta

Posters
84.
CHaraCTERIZATION OF β-N-ACETYLHEXOSAMINIDASE IN LEavES OF
TOBACCO PLANTS
Helena Ryšlavá 1 , Veronika Doubnerová 1 , Robert Valenta 1 , Kateřina Kloudová 1 ,
Jana Trefancová 1 , Helena Synková 2 and Noemi Čeřovská 2
1
Department of Biochemistry, Faculty of Natural Science, Charles University in Prague,
2
Institute of Experimental Botany AS CR
Plant glycosidases were characterized in seeds, but there is little information about these
enzymes in leaves. In tobacco plants (Nicotiana tabacum L., cv. Petit Havana, SR1) the
activity of α-glucosidase (EC 3.2.1.20), β-glucosidase (EC 3.2.1.21), α-galactosidase (EC
3.2.1.22), β-galactosidase (EC 3.2.1.23), α-mannosidase (EC 3.2.1.24) and activity of β-Nacetyl-hexosaminidase
(EC 3.2.1.52) were determined. The highest activity was found
for β-N-acetyl-hexosaminidase, this enzyme was able to hydrolyze both chromogenic
substrates p-NP-GlcNAc and p-NP-GalNAc. The products of the reaction were found to
be non-competitive inhibitors of the reactions catalyzed by β-N-acetyl-hexosaminidase.
The hydrolysis of another substrate -chitobiose was studied by capillary electrophoresis.
The size of β-N-acetyl-hexosaminidase molecule was estimated at 245 000. Under biotic
stress caused by viral infection enhanced activity of β-N-acetyl-hexosaminidase was found.
Acknowledgements: This work was supported by the grants of Ministry of Education of
the Czech Republic (grants MSM0021620808 and 1M0505).
XXII. Biochemistry Congress, Martin
207