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<p>The functional role of the carbohydrate-binding module family 20 (CBM20) in a raw starch-degrading α-amylase (HL11Amy) from <i>Roseateles terrae</i> HL11 was investigated through comparison with a CBM20-truncated variant (HL11AmyΔCBM20). Both enzymes exhibited optimal activity at 40&#xa0;°C and pH 4.0. HL11Amy showed superior performance in raw starch hydrolysis, producing higher levels of reducing sugars, whereas HL11AmyΔCBM20 exhibited enhanced activity toward gelatinized starch. Kinetic analysis revealed that HL11Amy consistently had lower K<sub>m</sub> values for soluble, rice, and cassava starches, indicating higher substrate affinity, while HL11AmyΔCBM20 displayed higher V<sub>max</sub> values for rice and cassava starches. Thin-layer chromatography (TLC) and scanning electron microscopy (SEM) further confirmed that CBM20 is essential for effective binding to and degradation of raw starch granules. These results demonstrate that CBM20 plays a key role in substrate recognition and efficient raw starch utilization, while its removal alters catalytic behavior toward processed substrates. The findings provide mechanistic insights into the intrinsic catalytic properties of HL11Amy and highlight the potential of CBM20-containing α-amylases for energy-efficient starch processing through direct hydrolysis of native starch, thereby reducing energy input and industrial costs.</p>

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Influence of carbohydrate-binding module family 20 (CBM20) removal on catalytic efficiency and substrate specificity of α-amylase from Roseateles terrae HL11

  • 期刊论文

  • 发表日期：

    2026年6月16日

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  • Mathurada Pheahom,
  • Benjarat Bunterngsook,
  • Daran Prongjit,
  • Hataikarn Lekakarn

摘要

The functional role of the carbohydrate-binding module family 20 (CBM20) in a raw starch-degrading α-amylase (HL11Amy) from Roseateles terrae HL11 was investigated through comparison with a CBM20-truncated variant (HL11AmyΔCBM20). Both enzymes exhibited optimal activity at 40 °C and pH 4.0. HL11Amy showed superior performance in raw starch hydrolysis, producing higher levels of reducing sugars, whereas HL11AmyΔCBM20 exhibited enhanced activity toward gelatinized starch. Kinetic analysis revealed that HL11Amy consistently had lower Km values for soluble, rice, and cassava starches, indicating higher substrate affinity, while HL11AmyΔCBM20 displayed higher Vmax values for rice and cassava starches. Thin-layer chromatography (TLC) and scanning electron microscopy (SEM) further confirmed that CBM20 is essential for effective binding to and degradation of raw starch granules. These results demonstrate that CBM20 plays a key role in substrate recognition and efficient raw starch utilization, while its removal alters catalytic behavior toward processed substrates. The findings provide mechanistic insights into the intrinsic catalytic properties of HL11Amy and highlight the potential of CBM20-containing α-amylases for energy-efficient starch processing through direct hydrolysis of native starch, thereby reducing energy input and industrial costs.