Structural highlights
Function
[GLGB_RHOMR] Catalyzes the formation of the alpha-1,6-glucosidic linkages in glycogen by scission of a 1,4-alpha-linked oligosaccharide from growing alpha-1,4-glucan chains and the subsequent attachment of the oligosaccharide to the alpha-1,6 position.
Publication Abstract from PubMed
A gene encoding 1,4-alpha-glucan branching enzyme (GBE, EC 2.4.1.18) from the extremely thermophilic bacterium Rhodothermus obamensis STB05 was successfully cloned and expressed in Escherichia coli. Extracellular expression of the recombinant enzyme (R.o-GBE) was achieved with a yield of 1080mg/L. Then it was purified and further characterized biochemically. R.o-GBE was optimally active at pH 7.0 and 65 degrees C. It remained stable at temperatures up to 80 degrees C and had a half-life at 85 degrees C of approximately 31min. Far-UV circular dichroism and intrinsic fluorescence analyses revealed that high temperatures reduced its activity by changing the secondary and tertiary structure of R.o-GBE. The enzyme had broad pH stability between pH 3.0 and 11.0at 4 degrees C, and preferred weakly acidic conditions at high temperatures. None of the metal ions enhanced the activity of R.o-GBE, but Ca(2+) may be required for its activity. Its specific activity with amylopectin was 6651 U/mg, which is much higher than that reported for other GBEs. Its excellent thermostability, broad pH stability, and high specific activity make R.o-GBE highly suitable for industrial applications.
Expression and characterization of an extremely thermophilic 1,4-alpha-glucan branching enzyme from Rhodothermus obamensis STB05.,Wang Z, Xin C, Li C, Gu Z, Cheng L, Hong Y, Ban X, Li Z Protein Expr Purif. 2019 Dec;164:105478. doi: 10.1016/j.pep.2019.105478. Epub, 2019 Aug 14. PMID:31421223[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Wang Z, Xin C, Li C, Gu Z, Cheng L, Hong Y, Ban X, Li Z. Expression and characterization of an extremely thermophilic 1,4-alpha-glucan branching enzyme from Rhodothermus obamensis STB05. Protein Expr Purif. 2019 Dec;164:105478. doi: 10.1016/j.pep.2019.105478. Epub, 2019 Aug 14. PMID:31421223 doi:http://dx.doi.org/10.1016/j.pep.2019.105478
