Expression of a secretory α-glucosidase II from Apis cerana indica in Pichia pastoris and its characterization

Table 3 Kinetic parameters ^a for the hydrolysis of different substrates by the partial purified r Aci HBGase II-(His) ₆ enzyme

Substrate	K _m ^b	k ₀	V _max ^c	k₀/K_m
Substrate	(mM)	(s^-1)	(mg glucose/min/mg protein)	(mM^-1·s^-1)
Maltotriose	26.7 ± 1.96	26.6 ± 0.88	3.94 ± 0.13	1.00
Maltotetraose	25.0 ± 3.10	2.84 ± 0.31	0.42 ± 0.04	0.11
Isomaltose	22.3 ± 3.49	5.2 ± 0.46	0.77 ± 0.07	0.23
Sucrose	15.3 ± 0.87	845.0 ± 0.00	125.0 ± 0.00	55.4
Soluble starch	22.0 ± 1.28	4.60 ± 0.14	0.68 ± 0.04	0.21
PNPG	4.20 ± 0.18	1.89 ± 0.11	0.28 ± 0.02	0.45

^aData are shown as the mean ± 1 SD and are derived from three independent repeats.
^bThe K_m value is the substrate concentration giving one half of the intrinsic V_max.
^cV_max was obtained from the calculated value as the glucose liberated from the reducing end residue of substrates.

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