Enzyme Research

Research Article

Improved Enzyme Catalytic Characteristics upon Glutaraldehyde Cross-Linking of Alginate Entrapped Xylanase Isolated from Aspergillus flavus MTCC 9390

Table 1

(a) Effect of cross-linking on the process parameters and activity of entrapped and cross-linked xylanase from A. flavus MTCC 9390. (b) Effect of metal ions and some chemicals on different forms of xylanase activity from A. flavus MTCC 9390.

(a)


Preparations	Theoretical maximal bound activity (U)	Unbound activity (U)	Bound (actual) activity (U)	Immobilization efficiency	Activity retention^#	Fold enrichment^†

Entrapped	114.67 ± 4.15	98.55 ± 3.06	87.4 ± 3.63	76 ± 2.24	53 ± 3.55	41 ± 3.00
Cross-linked	210.14 ± 6.31	3.08 ± 0.35	194.75 ± 6.53	92 ± 3.17	99 ± 3.78	91 ± 7.00

Immobilization efficiency = (actual bound activity/maximum theoretical bound activity) × 100.
^#Activity retention = (maximum theoretical bound activity/total activity employed for immobilization) × 100.
^†Fold enrichment = (actual bound activity/total activity employed for immobilization) × 100.
Note: immobilization effectiveness factor can be calculated from immobilization efficiency by dividing it with 100. Immobilization yield can be calculated from fold enrichment by dividing it with 100.
Enzyme units used for the immobilization: 213.22 UmL⁻¹.

(b)


	Residual activity (%)
	Free enzyme	Entrapped enzyme	Cross-linked

Metal ions (5 mM)
NaCl	124.9 ± 5.66	73.6 ± 2.92	74.2 ± 3.21
KCl	166.6 ± 6.84	92.1 ± 4.25	96.9 ± 4.47
MgCl₂	93.8 ± 3.62	57.5 ± 2.43	63.5 ± 3.02
CaCl₂	84.6 ± 2.68	87.6 ± 3.73	80.6 ± 3.45
CoCl₂	33.4 ± 1.32	41.1 ± 1.64	38.0 ± 1.12
HgCl₂	9.8 ± 1.02	37.04 ± 2.46	39.9 ± 1.82
CdCl₂	15.9 ± 1.68	36.8 ± 2.37	35.9 ± 2.54
NiCl₂	59.9 ± 5.23	47.4 ± 4.02	49.8 ± 4.17
Lead acetate	35.2 ± 2.63	73.2 ± 3.61	78.9 ± 4.23
Chemicals (1 mM)
PMSF	97.3 ± 5.62	104.9 ± 6.10	127.3 ± 6.55
PHMB^#	4.7 ± 0.58	34.7 ± 2.81	47.6 ± 3.19
DTNB^†	5.0 ± 0.95	29.4 ± 1.66	53.2 ± 2.58
EDTA^‡	90.8 ± 6.24	82.71 ± 5.77	84.5 ± 5.29

PMSF: phenylmethanesulfonyl fluoride.
^#PHMB: para-hydroxymercurybenzoate.
^†DTNB: 5,5′-dithiobis-(2-nitrobenzoic acid).
^‡EDTA: ethylenediaminetetraacetic acid.