scholarly journals Epoxyalkyl glycosides of d-xylose and xylo-oligosaccharides are active-site markers of xylanases from glycoside hydrolase family 11, not from family 10

2000 ◽  
Vol 347 (3) ◽  
pp. 865-873 ◽  
Author(s):  
Patricia NTARIMA ◽  
Wim NERINCKX ◽  
Klaus KLARSKOV ◽  
Bart DEVREESE ◽  
Mahalingeshwara K. BHAT ◽  
...  

A series of Ω-epoxyalkyl glycosides of D-xylopyranose, xylobiose and xylotriose were tested as potential active-site-directed inhibitors of xylanases from glycoside hydrolase families 10 and 11. Whereas family-10 enzymes (Thermoascus aurantiacus Xyn and Clostridium thermocellum Xyn Z) are resistant to electrophilic attack of active-site carboxyl residues, glycoside hydrolases of family 11 (Thermomyces lanuginosus Xyn and Trichoderma reesei Xyn II) are irreversibly inhibited. The apparent inactivation and association constants (ki, 1/Ki) are one order of magnitude higher for the xylobiose and xylotriose derivatives. The effects of the aglycone chain length can clearly be described. Xylobiose and n-alkyl β-D-xylopyranosides are competitive ligands and provide protection against inactivation. MS measurements showed 1:1 stoichiometries in most labelling experiments. Electrospray ionization MS/MS analysis revealed the nucleophile Glu86 as the modified residue in the T. lanuginosus xylanase when 2,3-epoxypropyl β-D-xylopyranoside was used, whereas the acid/base catalyst Glu178 was modified by the 3,4-epoxybutyl derivative. The active-site residues Glu86 and Glu177 in T. reesei Xyn II are similarly modified, confirming earlier X-ray crystallographic data [Havukainen, Törrönen, Laitinen and Rouvinen (1996) Biochemistry 35, 9617-9624]. The inability of the Ω-epoxyalkyl xylo(oligo)saccharide derivatives to inactivate family-10 enzymes is discussed in terms of different ligand-subsite interactions.

2005 ◽  
Vol 354 (2) ◽  
pp. 425-435 ◽  
Author(s):  
T. Collins ◽  
D. De Vos ◽  
A. Hoyoux ◽  
S.N. Savvides ◽  
C. Gerday ◽  
...  

Author(s):  
Justyna E. Korczynska ◽  
Steffen Danielsen ◽  
Ulrika Schagerlöf ◽  
Johan P. Turkenburg ◽  
Gideon J. Davies ◽  
...  

Lysins are important biomolecules which cleave the bacterial cell-wall polymer peptidoglycan. They are finding increasing commercial and medical application. In order to gain an insight into the mechanism by which these enzymes operate, the X-ray structure of a CAZy family GH25 `lysozyme' fromAspergillus fumigatuswas determined. This is the first fungal structure from the family and reveals a modified α/β-barrel-like fold in which an eight-stranded β-barrel is flanked by three α-helices. The active site lies toward the bottom of a negatively charged pocket and its layout has much in common with other solved members of the GH25 and related GH families. A conserved active-site DXE motif may be implicated in catalysis, lending further weight to the argument that this glycoside hydrolase family operatesviaa `substrate-assisted' catalytic mechanism.


2000 ◽  
Vol 347 (3) ◽  
pp. 865 ◽  
Author(s):  
Patricia NTARIMA ◽  
Wim NERINCKX ◽  
Klaus KLARSKOV ◽  
Bart DEVREESE ◽  
Mahalingeshwara K. BHAT ◽  
...  

Author(s):  
Fernando Segato ◽  
Gabriela L. Berto ◽  
Evandro Ares de Araújo ◽  
João Renato Muniz ◽  
Igor Polikarpov

Endoglucanases are important enzymes that are involved in the modification and degradation of cellulose. Filamentous fungi such asAspergillus terreusare effective biomass degraders in nature owing to their capacity to produce an enzymatic arsenal of glycoside hydrolases, including endoglucanase from glycoside hydrolase family 12 (GH12). TheA. terreusGH12 endoglucanase was cloned and overexpressed inA. nidulans, purified and crystallized. A single crystal was obtained from a solution consisting of 2 Mammonium sulfate, 5%(v/v) 2-propanol. X-ray diffraction data were collected to a resolution of 1.85 Å using synchrotron radiation and a preliminary molecular-replacement solution was obtained in the trigonal space groupP3221. The unit-cell parameters werea=b= 103.24,c= 48.96 Å.


2018 ◽  
Vol 293 (47) ◽  
pp. 18138-18150 ◽  
Author(s):  
Léa Chuzel ◽  
Mehul B. Ganatra ◽  
Erdmann Rapp ◽  
Bernard Henrissat ◽  
Christopher H. Taron

Exosialidases are glycoside hydrolases that remove a single terminal sialic acid residue from oligosaccharides. They are widely distributed in biology, having been found in prokaryotes, eukaryotes, and certain viruses. Most characterized prokaryotic sialidases are from organisms that are pathogenic or commensal with mammals. However, in this study, we used functional metagenomic screening to seek microbial sialidases encoded by environmental DNA isolated from an extreme ecological niche, a thermal spring. Using recombinant expression of potential exosialidase candidates and a fluorogenic sialidase substrate, we discovered an exosialidase having no homology to known sialidases. Phylogenetic analysis indicated that this protein is a member of a small family of bacterial proteins of previously unknown function. Proton NMR revealed that this enzyme functions via an inverting catalytic mechanism, a biochemical property that is distinct from those of known exosialidases. This unique inverting exosialidase defines a new CAZy glycoside hydrolase family we have designated GH156.


2015 ◽  
Vol 290 (19) ◽  
pp. 11819-11832 ◽  
Author(s):  
Christopher M. Bianchetti ◽  
Taichi E. Takasuka ◽  
Sam Deutsch ◽  
Hannah S. Udell ◽  
Eric J. Yik ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document