Ca. Hale et al., ARGINASE FROM KIWIFRUIT - PROPERTIES AND SEASONAL-VARIATION, New Zealand journal of crop and horticultural science, 25(3), 1997, pp. 295-301
The in vitro activity of arginase (EC 3.5.3.1) was investigated in you
ngest-mature leaves and roots (1-3 mm diameter) of kiwifruit vines (Ac
tinidia deliciosa var. deliciosa) during an annual growth cycle, and e
nzyme from root material partially purified. No seasonal trend in the
specific activity of arginase was observed in roots. Measurements in l
eaves, however, rose gradually during early growth and plateaued c. 17
weeks after budbreak. Changes in arginase activity were not correlate
d with changes in the concentration of arginine (substrate) or glutami
ne (likely end-product of arginine catabolism) in either tissue during
the growth cycle. Purification was by (NH4)(2)SO4 precipitation and D
EAE-cellulose chromatography. The kinetic properties of the enzyme, pu
rified 60-fold over that in crude extracts, indicated a pH optimum of
8.8, and a K-m (L-arginine) of 7.85 mM. Partially-purified enzyme was
deactivated by dialysis against EDTA, and reactivated in the presence
of Mn2+, Co2+, and Ni2+.