Structure and function of the type III pullulan hydrolase fromThermococcus kodakarensis
| Autor: | Steve P. Wood, Jonathan B. Cooper, Jingxu Guo, M. Akhtar, Alun R. Coker, Nasir Ahmad, Ronan M. Keegan, Majida Atta Muhammad, Naeem Rashid |
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| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
Glycoside Hydrolases Protein Conformation Stereochemistry Crystallography X-Ray 03 medical and health sciences chemistry.chemical_compound Protein Domains Structural Biology Catalytic Domain Hydrolase Maltotriose Thermostability 030102 biochemistry & molecular biology biology Pullulanase Protein Stability Hydrolysis Pullulan Maltose biology.organism_classification Thermococcus kodakarensis PANOSE Thermococcus 030104 developmental biology chemistry Amylases |
| Zdroj: | Acta Crystallographica Section D Structural Biology. 74:305-314 |
| ISSN: | 2059-7983 |
| DOI: | 10.1107/s2059798318001754 |
| Popis: | Pullulan-hydrolysing enzymes, more commonly known as debranching enzymes for starch and other polysaccharides, are of great interest and have been widely used in the starch-saccharification industry. Type III pullulan hydrolase fromThermococcus kodakarensis(TK-PUL) possesses both pullulanase and α-amylase activities. Until now, only two enzymes in this class, which are capable of hydrolysing both α-1,4- and α-1,6-glycosidic bonds in pullulan to produce a mixture of maltose, panose and maltotriose, have been described. TK-PUL shows highest activity in the temperature range 95–100°C and has a pH optimum in the range 3.5–4.2. Its unique ability to hydrolyse maltotriose into maltose and glucose has not been reported for other homologous enzymes. The crystal structure of TK-PUL has been determined at a resolution of 2.8 Å and represents the first analysis of a type III pullulan hydrolyse. The structure reveals that the last part of the N-terminal domain and the C-terminal domain are significantly different from homologous structures. In addition, the loop regions at the active-site end of the central catalytic domain are quite different. The enzyme has a well defined calcium-binding site and possesses a rare vicinal disulfide bridge. The thermostability of TK-PUL and its homologues may be attributable to several factors, including the increased content of salt bridges, helical segments, Pro, Arg and Tyr residues and the decreased content of serine. |
| Databáze: | OpenAIRE |
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