α-Glucosidase, rice

Rice-derived α-glucosidase（α-Glucosidase，CAS No.：9001-42-7）is a type III enzyme in the glycoside hydrolase GH31 family，primarily encoded by three genes，ONG1、ONG2、ONG3，of which ONG2 and ONG3 are generated by alternative splicing from the same genomic locus；the full-length translation product of the ONG2 gene can undergo post-translational proteolytic processing in its N-terminal region to generate two active isoforms，ONG2-I and ONG2-II，each of which forms a native functional enzyme through the tight association of a 6 kDa small peptide subunit and an 88 kDa large peptide subunit。These enzymes have an optimum pH of 4.5，remain stable over the broad pH range of 2.5~10.5，retain full activity below 40℃，and are completely inactivated after 10 min at 60℃；they have a broad substrate spectrum and can hydrolyze various glycosidic linkages，including α-1,4、α-1,2、α-1,3、α-1,6，with significantly higher hydrolytic activity toward long-chain maltooligosaccharides and soluble starch than toward small-molecule glycosides，and both ONG2 isoforms can directly bind to and degrade native rice starch granules，with ONG2-II showing 2 times the starch-granule binding capacity and 1.4 times the degradation rate of ONG2-I，respectively。

References：

[1] Nakai H, Ito T, Hayashi M, Kamiya K, Yamamoto T, Matsubara K, Kim YM, Jintanart W, Okuyama M, Mori H, Chiba S, Sano Y, Kimura A. Multiple forms of alpha-glucosidase in rice seeds (Oryza sativa L., var Nipponbare). Biochimie. 2007 Jan;89(1):49-62. doi: 10.1016/j.biochi.2006.09.014. Epub 2006 Oct 11. PMID: 17056172.