Crystallization and preliminary crystallographic analysis of endo-1,3-beta-glucanase from Arthrobacter sp.

Endo-1,3-beta-glucanases hydrolyze internal 1,3-beta-glucosyl linkages. The endo-1,3-beta-glucanase from Arthrobacter sp. was crystallized by the hanging-drop vapour-diffusion method. The crystals belonged to space group P4(1), with unit-cell parameters a = 71.31, c = 60.07 A, and contained one molecule per asymmetric unit. The Matthews coefficient (VM) and the solvent content were 2.35 A3 Da(-1) and 47.63%, respectively. Diffraction data were collected to a resolution of 1.66 A at SPring-8 using a MAR CCD area detector and gave a data set with an overall Rmerge of 5.4% and a completeness of 99.4%.

Structure of beta-glucan oligomer from laminarin and its effect on human monocytes to inhibit the proliferation of U937 cells.

We analyzed the human monocyte-stimulating ability of laminarin from Eisenia bicyclis, lichenan from Cetraria islandica, and their oligomers depolymerized with endo-1,3-beta-glucanase from Arthrobacter sp. The respective beta-glucan oligomers with different degrees of polymerization (DP) were fractionated from hydrolytic products of laminarin and lichenan using gel-filtration chromatography. The monocyte-conditioned medium pre-cultured in the presence of a fraction of beta-glucan oligomer (DP>/=8) from laminarin exhibited inhibitory activity against the proliferation of human myeloid leukemia U937 cells, while those pre-cultured with other beta-glucan oligomers and the original laminarin and lichenan showed little or no activity. NMR analysis indicated that the beta-glucan oligomer (DP>/=8) has an average DP value of 13, and its ratio of beta-1,3- to beta-1,6-linkages in glucopyranose units was estimated to be 1.3:1. These results indicate that the beta-1,3-glucan oligomer with a higher content of beta-1,6-linkage stimulates monocytes to inhibit the proliferation of U937 cells.