TABLE 3.

Thermostability and pH and temperature option of T. maritima xylanases XynA and XynB

Enzyme	Half-life at temp. (°C) ofa:			pH characteristics		Temp. characteristics
	95	90	85	pH optimumb	50% of maximum activityc retained at pH:	Temp. optimuma (°C)	50% of maximum activityc retained at temp. (°C):
XynAd	12 h	22 h	NLe	6.3	5.1–8.1	>98	NDf
XynB	<10 min	8 h	NL	6.5	5.5–7.4	87	64–98
XynBcat	1.5 min	4 min	3 h	6.5	6.1–7.4	70	52–80
XynC	ND	ND	ND	6.5	5.8–7.4	90	80–95

^aEnzymes were incubated in 25 mM bis-Tris propane, pH 6.5, in the absence of substrate. 

^bDetermined at 85°C in 25 mM bis-Tris propane adjusted to specified pH. 

^cEnzyme activity measured as the release of reducing sugars from birchwood xylan, as previously described (6). 

^dData for XynA are from reference 18 and D. J. Saul (unpublished). 

^eNL, no detectable loss after 16 h. 

^fND, not done.