Analysis of regulatory mechanism after ErbB4 gene mutation based on local modeling methodology.

ErbB4 is an oncogene belonging to the epidermal growth factor receptor family and contributes to the occurrence and development of multiple cancers, such as gastric, breast, and colorectal cancers. Therefore, studies of the regulation of ErbB4 in cancerigenic pathway will advance molecular targeted therapy. Advanced bioinformatic analysis softwares, such as ExPASy, Predictprotei, QUARK, and I-TASSER, were used to analyze the regulatory mechanism after ErbB4 gene mutation in terms of amino acid sequence, primary, secondary, and tertiary structure of the protein and upstream-downstream receptor/ligands. Mutation of the 19th and 113th amino acids at the carboxyl terminus of ErbB4 protein did not affect its biological nature, but its secondary structure changed and protein binding sites were near 2 mutational sites; moreover, after mutation introduction, additional binding sites were observed. Tertiary structure modeling indicated that local structure of ErbB4 was changed from an α helical conformation into a ß chain folding structure; the α helical conformation is the functional site of protein, while active sites are typically near junctions between helical regions, thus the helical structures are easily destroyed and change into folding structures or other structures after stretching. Mutable sites of ErbB4 is exact binding sites where dimer formed with other epidermal growth factor family proteins; mutation enabled the ErbB4 receptor to bind to neuregulin 1 ligand without dimer formation, disrupting the signal transduction pathway and affecting ErbB4 function.

Characterization of residual lignin after SO(2)-catalyzed steam explosion and enzymatic hydrolysis of Eucalyptus viminalis wood chips.

The lignin component found in both water insoluble (WI) and water and alkali insoluble (WIA) fractions derived from SO(2)-impregnated steam-exploded eucalyptus chips (SEE) was isolated and characterized. Dioxane lignins with a sugar content lower than 2% (w/w) were obtained after each material was treated with commercial cellulases. The C9 formulas of both SEE-WI and SEE-WIA dioxane lignins were C(9)H(6.83)N(0.04)O(2.24)(OCH(3))(1.21)(OH(aro))(0.56)(OH(ali))(0. 77) and C(9)H(8.65)N(0.29)O(1.97)(OCH(3))(0.90)(OH(aro))(0. 46)(OH(ali))(1.02), respectively. The weight-average molecular weight (M(w)) of the SEE-WI lignin corresponded to 3.85 kDa, whereas the SEE-WIA lignin had an M(w) of 3.66 kDa for the same polydispersity of 2.4. The SEE-WIA lignin was shown to be more thermally stable than the SEE-WI lignin, requiring temperatures in the range of 520 degrees C for complete degradation. FTIR and (1)H NMR analyses of both untreated and peracetylated lignin fractions showed that (a) the alkali insoluble lignin contained a relatively higher degree of substitution in aromatic rings per C9 unit and that (b) alkaline extraction removed lignin fragments containing appreciable amounts of phenolic hydroxyl groups.