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The Importance of Surface-Binding Site towards Starch-Adsorptivity Level in a-Amylase: A Review on Structural Point of View

The Importance of Surface-Binding Site towards Starch-Adsorptivity Level in a-Amylase: A Review on Structural Point of View
Umi Baroroh, Muhammad Yusuf, Saadah Diana Rachman, Safri Ishmayana, Mas Rizky A. A. Syamsunarno, Jutti Levita, Toto Subroto
Universitas Padjadjaran,Hindawi Enzyme Research 2017, Article ID 4086845
Bahasa Inggris
Universitas Padjadjaran,Hindawi Enzyme Research 2017, Article ID 4086845

Starch is a polymeric carbohydrate composed of glucose. As a source of energy, starch can be degraded by various amylolytic enzymes, including a-amylase. In a large-scale industry, starch processing cost is still expensive due to the requirement of high temperature during the gelatinization step. Therefore, ??-amylase with raw starch digesting ability could decrease the energy cost by avoiding the high gelatinization temperature. It is known that the carbohydrate-binding module (CBM) and the surface-binding site (SBS) of a-amylase could facilitate the substrate binding to the enzyme’s active site to enhance the starch digestion. These sites are a noncatalytic module, which could interact with a lengthy substrate such as insoluble starch. The major interaction between these sites and the substrate is the CH/pi-stacking interaction with the glucose ring. Several mutation studies on the Halothermothrix orenii,SusGBacteroides thetaiotamicron, Barley, Aspergillus niger,andSaccharomycopsis fibuligera a-amylases have revealed that the stacking interaction through the aromatic residues at the SBS is essential to the starch adsorption. In this review, the structural appearance of SBS in various a-amylases is also presented. Therefore, based on the structural point of view, SBS is suggested as an essential site in ??-amylase to increase its catalytic activity, especially towards the insoluble starch.

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