EFFECT OF SOME POLLUTED METALS ON THE ACTIVITY AND
KINETICS OF IMMOBILIZED GLUCOSE ISOMERASE
(SWEETZYME TYPE-T) FROM Streptomyces murinus.
BY
Foda, F.F. and Abd EI-Rahman, A.ئ
Dept. of Agric. Biochem., Fac. of Agric., Moshrohor. Zagazig Univ. Banha
Branch
ABSTRACT
The effect of sodium (N&), potassium (K) and manganese (Mn) ions
on the reaction activity of immobilized glucose isomerase (Sweetzyme type-T)
indicated that these ions act as activators in the reaction mixture. The reaction
activity was stimulated with increasing the above ions concentration up to 004M
in the presence of (O . 0 1 M) Mg ions. The percentage increment of activity were
95.31%., 8648% and 115.21% relative to control at concentration 004M of Na,
K and MiC ions. respectively. However, the results indicated that Cu, Hg,
Ca and t ions act as inhibitors in the reaction media. The sweetzyme type-T
lost 98.22%, 98.3 1, 99.91% and 96.24 of its activity after the addition ofO.7 M of
Ca, FC , Cu and Hg4 ions, respectively.
Reaction kinetics of immobilized glucose isomerase enzyme (sweetzyme
type-T) was found to be greatly affected by Cue, Hg, and M& ions. The
maximum reaction velocity (V) of the enzyme was decreased from 63.89
mM/L/min (in (he optimum condition ofthe enzyme) to 099 and 0.47 m.MIL/min
for Cu ions and to 7.33 and 4.67 mM/L/mىn for Hg ions at concentration of
0.01 and 0.04 M, respectively. On the other hand, the maximum reaction velocity
of this enzyme was increased from 63.89 inM/L/min to 1 19.06 and 137.5
inMIL/min hi presence of 0.01 and 0.04 M of Mn ions, respectively and to
102.78 and 127.9 mMJL/min in the absence ofO.O1M Mg ions under the above
concentrations of MiC, respectively. Michaelis constant (Km 0.37mM) was
constant in reactions with different concentrations in absence and presence of
metal ions. The results showed that noncompetitive type of inhibition occurred in
all cases. .