Mohammed Abdalla,Bo Jiang,Hinawi A.M. Hassanin,Luhua Zheng,Jingjing Chen
Maltodextrins (dextrins) are glucose chains normally produced by starch hydrolysis. Maltodextrins are characterized by their degree of polymerization (DP), which indicates the average number of glucose units per chain. Maltoheptaose (DP7), also known as amyloheptaose, is one of the maltodextrin mixtures widely used in foods, cosmetics, and pharmaceutical industries. Recently, the enzymatic synthesis of DP7 has attracted considerable attention, owing to its considerable advantages over chemical methods. In this work, we have designed a one-pot cascade reaction bio-synthesis starting from soluble starch to produce a specific degree of polymerization (DP7). The reaction system was catalyzed by cyclodextrin glucotransferase ( Ga CGT) from Gracilibacillus alcaliphilus SK51.001CGTase (transglycosylation/cyclization reaction) and cyclomaltodextrinase ( BsCD ) from Bacillus sphaericus E-244CDase (ring-opening reaction). The one-pot cascade reaction exhibited an optimum temperature of 30 °C and pH 7.0, and the addition of Ca 2+ enhanced the maltoheptaose production. The optimum enzyme units for the one-pot cascade reaction were 80 U/g of Ga CGT and 1 U/g of BsCD . However, the sequential addition of the enzymes exhibited a 5-fold higher conversion rate over simultaneous addition. The one-pot cascade reaction converted 30 g/L of soluble starch to 5.4 g/L of maltoheptaose in 1 h reaction time with a conversion rate of 16 %.
Siwen Wu,Yuling Yang,Shihan Wang,Chunyan Dong,Xueyan Zhang,Rui Zhang,Li Yang
Traumatic multidrug-resistant (MDR) bacterial infections are deadly threat to the public. To combat MDR bacteria, we developed a dual functional pH-sensitive hydrogel based on peptide DP7 (VQWRIRVAVIRK) and oxidized dextran (DP7-ODEX hydrogel). As an antimicrobial peptide , DP7 can synergize with many antibiotics; thus, we loaded ceftazidime into DP7-ODEX hydrogel, which showed an obvious advantage in MDR P. aeruginosa inhibition. Additionally, due to the interaction between aldehyde groups in oxidized dextran and amine groups from wound tissue, the hydrogel could extend on the irregular surface of skin defects and promote epithelial cells adhesion . DP7 could also be used as a wound-healing peptide and accelerate the healing process. We confirmed that the DP7-ODEX hydrogel exerted formidable therapeutic effects in normal or diabetic wound infection model. According to histomorphology analysis we found that DP7 hydrogel also have a scarless wound healing ability. In summary, we developed a hydrogel fabricated by the dual functional peptide DP7 that can kill multidrug-resistant bacteria colonizing the wound bed and boost scarless wound healing.
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