Activation of Galactanase from Penicillium citrinum by HgCl₂ and KCl

抄録

The activity of galactanase from Penicillium citrinum was enhanced by the addition of HgCl₂ and KC1 to the reaction mixture. The enhancement could be observed only when o-nitrophenyl-β-D-galactopyranoside (ONPG), p-nitrophenyl-β-D-galactopyranoside (PNPG), and β-1, 4-linked galactobiose were used as substrates, i.e., not when soy bean arabinogalactan and o-nitrophenyl galactobioside were used.
Among the metal ions tested, only HgCl₂ was effective. KCl could be replaced by KBr but not by KF or KI.
The extent of the activation depended on the concentrations of HgCl₂ and KCl, and the maximum activation (about 5.5-fold, as measured as the amount of o-nitrophenol liberated in a definite time) was observed when 0.1 IBM HgCl₂ and 25 mM KCl were added. The activity enhancement was also dependent on the concentration of ONPG. The activation was evident only when the concentration of the substrate was low and its extent decreased with an increase in the substrate concentration.