Acute glucose fluctuation during the postprandial period causes a risk for type 2 diabetes mellitus (T2DM). α-Glucosidase inhibitors have been approved as therapeutic agents for diabetes. In the present study, a protein with α-glucosidase inhibitory activity from Flax (Linum usitatissimum) seeds was isolated using a one-step purification with Q-Sepharose4B column, followed by Sephacryl S-200 size-exclusion chromatography. It was identified as a trypsin inhibitor, named L. usitatissimum trypsin inhibitor (LUTI). The half maximal inhibitory concentration (IC50) of LUTI was 113.92 μM for α-glucosidase and 6.17 μM for trypsin. Lineweaver-Burk kinetic experiment showed that the protein exhibited two distinct ... More
Acute glucose fluctuation during the postprandial period causes a risk for type 2 diabetes mellitus (T2DM). α-Glucosidase inhibitors have been approved as therapeutic agents for diabetes. In the present study, a protein with α-glucosidase inhibitory activity from Flax (Linum usitatissimum) seeds was isolated using a one-step purification with Q-Sepharose4B column, followed by Sephacryl S-200 size-exclusion chromatography. It was identified as a trypsin inhibitor, named L. usitatissimum trypsin inhibitor (LUTI). The half maximal inhibitory concentration (IC50) of LUTI was 113.92 μM for α-glucosidase and 6.17 μM for trypsin. Lineweaver-Burk kinetic experiment showed that the protein exhibited two distinct inhibitory modes, a competitive inhibitor type for α-glucosidase and a non-competitive type for trypsin. The interaction between LUTI and α-glucosidase was detected through gel filtration chromatography and dynamic light scattering. Increased glucose consumption and lactic acid production were also observed following LUTI treatment in Caco-2 and HepG2 cells. LUTI inhibits not only the activity of trypsin but also the activity of α-glucosidase. It is expected that LUTI will become an oral hypoglycemic polypeptide drug for T2DM.,© The Author(s) 2019. Published by Oxford University Press on behalf of the Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
