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Substrate specificity and subsite mobility in T. aurantiacus xylanase 10A
Author(s) -
Lo Leggio Leila,
Kalogiannis Stavros,
Eckert Kelvin,
Teixeira Susana C.M,
Bhat Mahalingeswara K,
Andrei Carmen,
Pickersgill Richard W,
Larsen Sine
Publication year - 2001
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(01)03177-5
Subject(s) - xylanase , xylobiose , chemistry , stereochemistry , context (archaeology) , ligand (biochemistry) , glycoside hydrolase , substrate (aquarium) , crystallography , anomer , protein subunit , biochemistry , enzyme , biology , receptor , paleontology , ecology , gene
The substrate specificity of Thermoascus aurantiacus xylanase 10A (TAX) has been investigated both biochemically and structurally. High resolution crystallographic analyses at 291 K and 100 K of TAX complexes with xylobiose show that the ligand is in its α anomeric conformation and provide a rationale for specificity on p ‐nitrophenyl glycosides at the −1 and −2 subsites. Trp 275, which is disordered in uncomplexed structures, is stabilised by its interaction with xylobiose. Two structural subsets in family 10 are identified, which differ by the presence or absence of a short helical stretch in the eighth βα‐loop of the TIM barrel, the loop bearing Trp 275. This structural difference is discussed in the context of Trp 275 mobility and xylanase function.