Abstract
Backgroundα-Amylases specifically catalyse the hydrolysis of the internal α-1, 4-glucosidic linkages of starch. Glycoside hydrolase (GH) family 13 is the main α-amylase family in the carbohydrate-active database. Lactobacillus plantarum WCFS1 possesses eleven proteins included in GH13 family. Among these, proteins annotated as maltose-forming α-amylase (Lp_0179) and maltogenic α-amylase (Lp_2757) were included.ResultsIn this study, Lp_0179 and Lp_2757 L. plantarum α-amylases were structurally and biochemically characterized. Lp_2757 displayed structural features typical of GH13_20 subfamily which were absent in Lp_0179. Genes encoding Lp_0179 (Amy2) and Lp_2757 were cloned and overexpressed in Escherichia coli BL21(DE3). Purified proteins showed high hydrolytic activity on pNP-α-D-maltopyranoside, being the catalytic efficiency of Lp_0179 remarkably higher. In relation to the hydrolysis of starch-related carbohydrates, Lp_0179 only hydrolysed maltopentaose and dextrin, demonstrating that is an exotype glucan hydrolase. However, Lp_2757 was also able to hydrolyze cyclodextrins and other non-cyclic oligo- and polysaccharides, revealing a great preference towards α-1,4-linkages typical of maltogenic amylases.ConclusionsThe substrate range as well as the biochemical properties exhibited by Lp_2757 maltogenic α-amylase suggest that this enzyme could be a very promising enzyme for the hydrolysis of α-1,4 glycosidic linkages present in a broad number of starch-carbohydrates, as well as for the investigation of an hypothetical transglucosylation activity under appropriate reaction conditions.
Highlights
Starch is the most popular polysaccharide used as a food ingredient. It is a mixture of amylose, which is essentially composed only of α-1,4-linked glucose-polymers, and amylopectin, which is composed of α-1,4-linked glucose-polymers branched by α-1,6 linkages. α-Amylase catalyse the hydrolysis of the internal α-1,4 glucosidic linkages of starch; in addition to its main reaction, α-amylase weakly catalyse α-1,4-transglycosylation [1]
Sequence analysis and structural features of L. plantarum α‐amylases As mentioned previously, family GH13 is known as the main α-amylase family in CAZy database
L. plantarum WCFS1 possesses eleven proteins included in GH13 family
Summary
Starch is the most popular polysaccharide used as a food ingredient. It is a mixture of amylose, which is essentially composed only of α-1,4-linked glucose-polymers, and amylopectin, which is composed of α-1,4-linked glucose-polymers branched by α-1,6 linkages. α-Amylase catalyse the hydrolysis of the internal α-1,4 glucosidic linkages of starch; in addition to its main reaction, α-amylase weakly catalyse α-1,4-transglycosylation [1]. An example is the assignment of different EC numbers for the same activity in subfamily GH13_20, which groups cyclomaltodextrinase (EC 3.2.1.54), maltogenic α-amylase (EC 3.2.1.133), and neopullulanase (EC 3.2.1.135), which are enzymes with strongly related (or even sometimes nearly identical) substrate and/ or product specificities [5, 6]. These enzymes are distinguished from typical α-amylases (EC 3.2.1.1) by containing an N-terminal domain and exhibiting preferential substrate specificities for cyclomaltodextrins over starch [6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
