Amylomaltase(AM)is a transglucosylase known for producing glucans exclusively withα-1,4 linkages,which is widely used in the industries for modification of starch.In this paper,a study was conducted to investigate bo...Amylomaltase(AM)is a transglucosylase known for producing glucans exclusively withα-1,4 linkages,which is widely used in the industries for modification of starch.In this paper,a study was conducted to investigate both the characteristics of recombinant amylomaltase from Thermus thermophilus STB20(TtAM)and its impact on the fine structure of tapioca starch.The TtAM showed an excellent thermostability and a high affinity for larger molecular substrates.Changes in the molecular characteristics of tapioca starch were discussed in terms of chain length distribution(CLD)and molecular weight distribution(M_(w))under different enzyme dosages and reaction times.The TtAM degraded amylose,which was transferred to short side chains(DP 11-26)of amylopectin,thereby extending short side chains into longer chains(DP>26).The M_(w)of TtAM-treated starches initially increased and then decreased.With increasing enzyme dosage and reaction time,the TtAM facilitated hydrolysis activities,reducing the proportion of long side chains,which led to increase the dextrose equivalent(DE)value.Cycloamylose(DP 8-33)was generated during the modification process,reflecting a diversified range of the enzyme products,and resulting in a polymodal distribution profile in the M_(w).These findings potentially broaden the utilization of TtAM in the production of starch conversion products,indicating that novel starch-based derivatives with tailor-made structures can be obtained by controlling the enzyme dosages and reaction times.展开更多
基金financially supported by the National Natural Science Foundation of China(No.32272263)the Science and Technology Support Program(Modern Agriculture)of Jiangsu Province,China(BE2022323).
文摘Amylomaltase(AM)is a transglucosylase known for producing glucans exclusively withα-1,4 linkages,which is widely used in the industries for modification of starch.In this paper,a study was conducted to investigate both the characteristics of recombinant amylomaltase from Thermus thermophilus STB20(TtAM)and its impact on the fine structure of tapioca starch.The TtAM showed an excellent thermostability and a high affinity for larger molecular substrates.Changes in the molecular characteristics of tapioca starch were discussed in terms of chain length distribution(CLD)and molecular weight distribution(M_(w))under different enzyme dosages and reaction times.The TtAM degraded amylose,which was transferred to short side chains(DP 11-26)of amylopectin,thereby extending short side chains into longer chains(DP>26).The M_(w)of TtAM-treated starches initially increased and then decreased.With increasing enzyme dosage and reaction time,the TtAM facilitated hydrolysis activities,reducing the proportion of long side chains,which led to increase the dextrose equivalent(DE)value.Cycloamylose(DP 8-33)was generated during the modification process,reflecting a diversified range of the enzyme products,and resulting in a polymodal distribution profile in the M_(w).These findings potentially broaden the utilization of TtAM in the production of starch conversion products,indicating that novel starch-based derivatives with tailor-made structures can be obtained by controlling the enzyme dosages and reaction times.
