An alpha-1,6-and alpha-1,3-linked glucan produced by Leuconostoc citreum ABK-1 alternansucrase with nanoparticle and film-forming properties

作者：Wangpaiboon Karan; Padungros Panuwat; Nakapong Santhana; Charoenwongpaiboon Thanapon; Rejzek Martin; Field Robert A; Pichyangkura Rath^*

来源：Scientific Reports, 2018, 8(1): 8340.

DOI：10.1038/s41598-018-26721-w

Alternansucrase catalyses the sequential transfer of glucose residues from sucrose onto another sucrose molecule to form a long chain polymer, known as "alternan". The alternansucrase-encoding gene from Leuconostoc citreum ABK-1 (Lcalt) was successfully cloned and expressed in Escherichia coli. Lcalt encoded LcALT of 2,057 amino acid residues; the enzyme possessed an optimum temperature and pH of 40 degrees C and 5.0, respectively, and its' activity was stimulated up to 2.4-fold by the presence of Mn2+. Kinetic studies of LcALT showed a high transglycosylation activity, with K-m 32.2 +/- 3.2 mM and kcat 290 +/- 12 s(-1). Alternan generated by LcALT (Lc-alternan) harbours partially alternating alpha-1,6 and alpha-1,3 glycosidic linkages confirmed by NMR spectroscopy, methylation analysis, and partial hydrolysis of Lc-alternan products. In contrast to previously reported alternans, Lc-alternan can undergo self-assembly, forming nanoparticles with an average size of 90 nm in solution. At concentrations above 15% (w/v), Lc-alternan nanoparticles disassemble and form a high viscosity solution, while this polymer forms a transparent film once dried.

• 出版日期2018-5-29