3.2.1.B26	additional information	-	an important role of the sequence segment present only in hyperthermophilic beta-glycosidases, in the thermal adaptation of archaea beta-glycosidases is hypothesized. The thermostabilization mechanism could occur as a consequence of numerous favorable ionic interactions of the 83–124 sequence with the other part of protein matrix that becomes more rigid and less accessible to the insult of thermal-activated solvent molecules	721008	
3.2.1.B26	additional information	-	inactivation is coupled to irreversible aggregation	722214	
3.2.1.B26	additional information	-	protein contains 68 tryptophans, two distinct classes of tryptophanyl residues that differ in microenvironmental characteristics. The conformational dynamics of the two classes of tryptophanyl residues is affected differently by temperature, suggesting that the protein regions in which they are located give different contributions to enzyme properties, such as flexibility, stability and function	724903	
3.2.1.B26	additional information	-	the conformational transitions of thermophilic beta-glycosidase from Sulfolobus solfataricus and the mechanism of its thermal and chemical activation are studied by electron paramagnetic resonance of nitroxide spin labels immobilized on the protein matrix	721362	
3.2.1.B26	additional information	-	the fluorescence emission is characterized by a bimodal lifetime distribution, suggesting that the enzyme structure contains rigid and flexible regions, properly located in the macromolecule. The enzyme activity and thermostability appear to be related to the dynamic properties of these regions as evidenced by perturbation studies of the enzyme structure at alkaline pH and by addition of detergents such as SDS. The pH increase affects the protein dynamics with a remarkable loss of thermal stability and activity; these changes occur without any significant variation in the secondary structure as revealed by far-UV dichroic measurements. In the presence of 0.02% (w/v) SDS at alkaline pH, the enzymatic activity and thermostability are recovered. Under these conditions, the conformational dynamics appear to be similar to that evidenced at neutral pH. Further inreases in SDS concentration, at alkaline pH, render the activity and thermostability of beta-glycosidase similar to those observed in the absence of detergent	721006	
3.2.1.B26	additional information	-	the thermostability is affected by the nature and charge of the cations, reaching maximal effects for the case of Mg2+. Cations can cause a strong attenuation of the ion pair interactions E474–K72 and D473–R402, with consequent partial dissociation of the tetrameric structure	724893	
3.2.1.B26	additional information	-	the thermostable enzyme is an interesting model system for the study of protein adaptation to high temperatures. The largest ion-pair network of the enzyme is located at the tetrameric interface of the molecule	721007	
3.2.1.B26	additional information	-	thermostability is not affected by the presence of Mg2+	724623	
3.2.1.B26	5	-	after a storage greater than 40 h at atmospheric pressure, the residual activity decreases	724406	
3.2.1.B26	30	100	pH 6.5, no denaturation occurrs in the temperature range of 30 to 100°C for both the native and recombinant enzyme	722128	
3.2.1.B26	60	-	72 h, stable	724154	
3.2.1.B26	60	-	maintains a half-life of 91 h at 60°C and 2.5 kbar	724406	
3.2.1.B26	70	-	1.5 h, no residual activity	724212	
3.2.1.B26	70	-	half-life: 700 h	724582	
3.2.1.B26	70	-	pH 5.5, immobilized enzyme, half-life: 10 days	724626	
3.2.1.B26	70	-	t1/2: 10 d	724623	
3.2.1.B26	75	-	30 min, 90% residual activity	722214	
3.2.1.B26	75	-	5 h, 17% loss of activity	326274	
3.2.1.B26	75	-	5 h, enzyme immobilized on chitosan activated with glutaraldehyde, 15% loss of activity	723982	
3.2.1.B26	75	-	90 min, 70% residual cell enzymatic activity in the aqueous phase	724622	
3.2.1.B26	75	-	half-life: 100 h	724582	
3.2.1.B26	80	-	half-life: 66 h	724582	
3.2.1.B26	80	-	t1/2: about 5 d	724623	
3.2.1.B26	85	-	5 h, 43% loss of activity	326274	
3.2.1.B26	85	-	5 h, enzyme immobilized on chitosan activated with glutaraldehyde, 25% loss of activity	723982	
3.2.1.B26	85	-	83% residual activity after 5 h	326274	
3.2.1.B26	85	-	denaturation temperature. The temperature-induced denaturation of this tetrameric enzyme is a complex and irreversible process, in which subunit dissociation is coupled with unfolding, while unfolded polypeptide chains tend to associate in a nonspecific manner	725304	
3.2.1.B26	85	-	half-life: 30 h	724582	
3.2.1.B26	85	-	half-life: 48 h	721468	
3.2.1.B26	85	-	k(inact): 0.0000061 (wild-type enzyme), 0.00012 (mutant enzyme R488A), 0.00029 (mutant enzyme H489A), 0.00001 (mutant enzyme delHis489)	721007	
3.2.1.B26	90	-	half-life: 1.7 h	724582	
3.2.1.B26	90	-	low concentrations of the detergent (up to 0.02%) induce slight changes in the enzyme secondary structure, whereas high concentrations cause the alpha-helix content to increase at high temperatures and prevent protein aggregation	718769	
3.2.1.B26	90	-	low concentrations of the SDS (up to 0.02%) induce slight changes in the enzyme secondary structure, whereas high concentrations cause the alpha-helix content to increase at high temperatures and prevent protein aggregation	718769	
3.2.1.B26	90	-	t1/2: 0.7 d	724623	
3.2.1.B26	92	-	half-life: less than 3 min	724212	
3.2.1.B26	97	98	Tm-value for recombinant enzyme	725356	
3.2.1.B26	98	99	Tm-value for native enzyme	725356	
3.2.1.B26	100	-	investigation of the activity and conformational dynamics above 100°C. The data indicate a strong correlation between enzyme activity and protein flexibility. In particular, the time-resolved fluorescence data point out that some regions of the protein structure are very sensitive to the temperature increases, gaining a high flexibility degree with temperature. On the other hand, it is also possible to identify local environments of the enzyme structure that still possess a relatively high rigidity at 125°C	719097