Glycogen Branching Enzyme with a Novel Chain Transfer Mode Derived from Corallococcus sp. Strain EGB and Its Potential Applications

Abstract

Dietary starch with an increased content of resistant starch (RS) has the potential to reduce the prevalence of diabetes, obesity, and cardiovascular diseases. Here, an efficient glycogen branching enzyme, CcGBE, from Corallococcus sp. strain EGB was identified, and its relevant properties, including potential application in the preparation of modified starch, were evaluated. The purified CcGBE exhibited a maximal specific activity of approximately 20,000 U/mg using cassava starch as the optimal substrate. The content of α-1,6-glucosidic bonds in CcGBE-modified cassava starch increased from 2.9 to 13.2%. Meanwhile, both the average chain length (CL) of CcGBE-modified starch and the blue value of the color complex formed by starch and iodine initially increased and then decreased, indicating that a new CL transfer mode was reported. Perforated small starch granules were released after CcGBE treatment, and a time-dependent decrease in the retrogradation enthalpy (ΔH r) of cassava starch indicated that CcGBE inhibited the long-term retrogradation of starch. Moreover, the RS content and cold water solubility (CWS) of CcGBE-modified starch increased from 3.3 to 12.8% and from 23.1 to 93.8%, respectively. These findings indicate the application potential of CcGBE for the preparation of modified starch with increased RS and CWS.

Comprehensive analysis of key host gene-microbe networks in the cecum tissues of the obese rabbits induced by a high-fat diet

“…A previous study found that the Corallococcus sp. strain was correlated with glucose metabolism in dietary starch and played an important regulatory role in the degradation of crude fiber in the body ( Ye et al., 2022 ). The cecum of rabbits is an important place for crude fiber digestion.…”

A novel xylanase from a myxobacterium triggers a plant immune response in Nicotiana benthamiana

“…The construction of recombinant plasmid pET‐29a (+)‐CcXyn was carried out using ClonExpress II One Step Cloning Kit (Vazyme Biotech Co. Ltd). The overexpression and purification of recombinant protein CcXyn were performed according to a previous report (Ye et al., 2022 ): E. coli BL21 (DE3) cells containing pET‐29a (+)‐CcXyn were cultured in Luria Bertani medium and induced with 0.2 mM isopropyl‐β‐ d ‐thiogalactopyranoside (Sigma‐Aldrich) at 16°C when OD 600 reached 0.5–0.6. The cells were harvested by centrifugation at 20,000 g and disrupted by sonication (Sonicator 201M) after suspending with 20 mM Tris–HCl buffer (pH 7.6).…”

“…were performed according to a previous report (Ye et al, 2022) as described previously (Laemmli, 1970).…”

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“…A previous study found that the Corallococcus sp. strain was correlated with glucose metabolism in dietary starch and played an important regulatory role in the degradation of crude fiber in the body (Ye et al, 2022). The cecum of rabbits is an important place for crude fiber digestion.…”