High stability and low competitive inhibition of thermophilic Thermopolyspora flexuosa GH10 xylanase in biomass-dissolving ionic liquids

Sasikala Anbarasan (Corresponding Author), Ronny Wahlström, Michael Hummel, Heikki Ojamo, Herbert Sixta, Ossi Turunen

Research output: Contribution to journalArticleScientificpeer-review

5 Citations (Scopus)

Abstract

Thermophilic Thermopolyspora flexuosa GH10 xylanase (TfXYN10A) was studied in the presence of biomass-dissolving hydrophilic ionic liquids (ILs) [EMIM]OAc, [EMIM]DMP and [DBNH]OAc. The temperature optimum of TfXYN10A with insoluble xylan in the pulp was at 65-70 °C, with solubilised 1 % xylan at 70-75 °C and with 3 % xylan at 75-80 °C. Therefore, the amount of soluble substrate affects the enzyme activity at high temperatures. The experiments with ILs were done with 1 % substrate. TfXYN10A can partially hydrolyse soluble xylan even in the presence of 40 % (v/v) ILs. Although ILs decrease the apparent temperature optimum, a surprising finding was that at the inactivating temperatures (80-90 °C), especially [EMIM]OAc increases the stability of TfXYN10A indicating that the binding of IL molecules strengthens the protein structure. Earlier kinetic studies showed an increased Km with ILs, indicating that ILs function as competitive inhibitors. TfXYN10A showed low increase of Km, which was 2-, 3- and 4-fold with 15 % [EMIM]OAc, [DBNH]OAc and [EMIM]DMP, respectively. One reason for the low competitive inhibition could be the high affinity to the substrate (low Km). Xylanases with low Km (~1 mg/mL) appear to show higher tolerance to ILs than xylanases with higher Km (~2 mg/mL). Capillary electrophoresis showed that TfXYN10A hydrolyses xylan to the end-products in 15-35 % ILs practically as completely as without IL, also indicating good binding of the short substrate molecules by TfXYN10A despite of major apparent IL binding sites above the catalytic residues. Substrate binding interactions in the active site appear to explain the high tolerance of TfXYN10A to ILs.
Original languageEnglish
Pages (from-to)1487-1498
Number of pages12
JournalApplied Microbiology and Biotechnology
Volume101
Issue number4
DOIs
Publication statusPublished - 1 Feb 2017
MoE publication typeA1 Journal article-refereed

Fingerprint

Ionic Liquids
Biomass
Xylans
Temperature
Capillary Electrophoresis
Catalytic Domain

Keywords

  • GH10 xylanase
  • Hydrophilic ionic liquids
  • Stability
  • Competitive inhibition
  • Substrate interaction
  • Active site modelling

Cite this

Anbarasan, Sasikala ; Wahlström, Ronny ; Hummel, Michael ; Ojamo, Heikki ; Sixta, Herbert ; Turunen, Ossi. / High stability and low competitive inhibition of thermophilic Thermopolyspora flexuosa GH10 xylanase in biomass-dissolving ionic liquids. In: Applied Microbiology and Biotechnology. 2017 ; Vol. 101, No. 4. pp. 1487-1498.
@article{5e8fd00070f44130a54a7139b9a2b06d,
title = "High stability and low competitive inhibition of thermophilic Thermopolyspora flexuosa GH10 xylanase in biomass-dissolving ionic liquids",
abstract = "Thermophilic Thermopolyspora flexuosa GH10 xylanase (TfXYN10A) was studied in the presence of biomass-dissolving hydrophilic ionic liquids (ILs) [EMIM]OAc, [EMIM]DMP and [DBNH]OAc. The temperature optimum of TfXYN10A with insoluble xylan in the pulp was at 65-70 °C, with solubilised 1 {\%} xylan at 70-75 °C and with 3 {\%} xylan at 75-80 °C. Therefore, the amount of soluble substrate affects the enzyme activity at high temperatures. The experiments with ILs were done with 1 {\%} substrate. TfXYN10A can partially hydrolyse soluble xylan even in the presence of 40 {\%} (v/v) ILs. Although ILs decrease the apparent temperature optimum, a surprising finding was that at the inactivating temperatures (80-90 °C), especially [EMIM]OAc increases the stability of TfXYN10A indicating that the binding of IL molecules strengthens the protein structure. Earlier kinetic studies showed an increased Km with ILs, indicating that ILs function as competitive inhibitors. TfXYN10A showed low increase of Km, which was 2-, 3- and 4-fold with 15 {\%} [EMIM]OAc, [DBNH]OAc and [EMIM]DMP, respectively. One reason for the low competitive inhibition could be the high affinity to the substrate (low Km). Xylanases with low Km (~1 mg/mL) appear to show higher tolerance to ILs than xylanases with higher Km (~2 mg/mL). Capillary electrophoresis showed that TfXYN10A hydrolyses xylan to the end-products in 15-35 {\%} ILs practically as completely as without IL, also indicating good binding of the short substrate molecules by TfXYN10A despite of major apparent IL binding sites above the catalytic residues. Substrate binding interactions in the active site appear to explain the high tolerance of TfXYN10A to ILs.",
keywords = "GH10 xylanase, Hydrophilic ionic liquids, Stability, Competitive inhibition, Substrate interaction, Active site modelling",
author = "Sasikala Anbarasan and Ronny Wahlstr{\"o}m and Michael Hummel and Heikki Ojamo and Herbert Sixta and Ossi Turunen",
note = "ISI: BIOTECHNOLOGY & APPLIED MICROBIOLOGY",
year = "2017",
month = "2",
day = "1",
doi = "10.1007/s00253-016-7922-9",
language = "English",
volume = "101",
pages = "1487--1498",
journal = "Applied Microbiology and Biotechnology",
issn = "0175-7598",
publisher = "Springer",
number = "4",

}

High stability and low competitive inhibition of thermophilic Thermopolyspora flexuosa GH10 xylanase in biomass-dissolving ionic liquids. / Anbarasan, Sasikala (Corresponding Author); Wahlström, Ronny; Hummel, Michael; Ojamo, Heikki; Sixta, Herbert; Turunen, Ossi.

In: Applied Microbiology and Biotechnology, Vol. 101, No. 4, 01.02.2017, p. 1487-1498.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - High stability and low competitive inhibition of thermophilic Thermopolyspora flexuosa GH10 xylanase in biomass-dissolving ionic liquids

AU - Anbarasan, Sasikala

AU - Wahlström, Ronny

AU - Hummel, Michael

AU - Ojamo, Heikki

AU - Sixta, Herbert

AU - Turunen, Ossi

N1 - ISI: BIOTECHNOLOGY & APPLIED MICROBIOLOGY

PY - 2017/2/1

Y1 - 2017/2/1

N2 - Thermophilic Thermopolyspora flexuosa GH10 xylanase (TfXYN10A) was studied in the presence of biomass-dissolving hydrophilic ionic liquids (ILs) [EMIM]OAc, [EMIM]DMP and [DBNH]OAc. The temperature optimum of TfXYN10A with insoluble xylan in the pulp was at 65-70 °C, with solubilised 1 % xylan at 70-75 °C and with 3 % xylan at 75-80 °C. Therefore, the amount of soluble substrate affects the enzyme activity at high temperatures. The experiments with ILs were done with 1 % substrate. TfXYN10A can partially hydrolyse soluble xylan even in the presence of 40 % (v/v) ILs. Although ILs decrease the apparent temperature optimum, a surprising finding was that at the inactivating temperatures (80-90 °C), especially [EMIM]OAc increases the stability of TfXYN10A indicating that the binding of IL molecules strengthens the protein structure. Earlier kinetic studies showed an increased Km with ILs, indicating that ILs function as competitive inhibitors. TfXYN10A showed low increase of Km, which was 2-, 3- and 4-fold with 15 % [EMIM]OAc, [DBNH]OAc and [EMIM]DMP, respectively. One reason for the low competitive inhibition could be the high affinity to the substrate (low Km). Xylanases with low Km (~1 mg/mL) appear to show higher tolerance to ILs than xylanases with higher Km (~2 mg/mL). Capillary electrophoresis showed that TfXYN10A hydrolyses xylan to the end-products in 15-35 % ILs practically as completely as without IL, also indicating good binding of the short substrate molecules by TfXYN10A despite of major apparent IL binding sites above the catalytic residues. Substrate binding interactions in the active site appear to explain the high tolerance of TfXYN10A to ILs.

AB - Thermophilic Thermopolyspora flexuosa GH10 xylanase (TfXYN10A) was studied in the presence of biomass-dissolving hydrophilic ionic liquids (ILs) [EMIM]OAc, [EMIM]DMP and [DBNH]OAc. The temperature optimum of TfXYN10A with insoluble xylan in the pulp was at 65-70 °C, with solubilised 1 % xylan at 70-75 °C and with 3 % xylan at 75-80 °C. Therefore, the amount of soluble substrate affects the enzyme activity at high temperatures. The experiments with ILs were done with 1 % substrate. TfXYN10A can partially hydrolyse soluble xylan even in the presence of 40 % (v/v) ILs. Although ILs decrease the apparent temperature optimum, a surprising finding was that at the inactivating temperatures (80-90 °C), especially [EMIM]OAc increases the stability of TfXYN10A indicating that the binding of IL molecules strengthens the protein structure. Earlier kinetic studies showed an increased Km with ILs, indicating that ILs function as competitive inhibitors. TfXYN10A showed low increase of Km, which was 2-, 3- and 4-fold with 15 % [EMIM]OAc, [DBNH]OAc and [EMIM]DMP, respectively. One reason for the low competitive inhibition could be the high affinity to the substrate (low Km). Xylanases with low Km (~1 mg/mL) appear to show higher tolerance to ILs than xylanases with higher Km (~2 mg/mL). Capillary electrophoresis showed that TfXYN10A hydrolyses xylan to the end-products in 15-35 % ILs practically as completely as without IL, also indicating good binding of the short substrate molecules by TfXYN10A despite of major apparent IL binding sites above the catalytic residues. Substrate binding interactions in the active site appear to explain the high tolerance of TfXYN10A to ILs.

KW - GH10 xylanase

KW - Hydrophilic ionic liquids

KW - Stability

KW - Competitive inhibition

KW - Substrate interaction

KW - Active site modelling

UR - http://www.scopus.com/inward/record.url?scp=84992109387&partnerID=8YFLogxK

U2 - 10.1007/s00253-016-7922-9

DO - 10.1007/s00253-016-7922-9

M3 - Article

VL - 101

SP - 1487

EP - 1498

JO - Applied Microbiology and Biotechnology

JF - Applied Microbiology and Biotechnology

SN - 0175-7598

IS - 4

ER -