Detailed investigation on the molecular structure of carboxymethyl cellulose with unusual substitution pattern by means of an enzyme-supported analysis

Abstract

Four carboxymethyl cellulose samples derived from the synthesis concept of “reaction in reactive microstructures” were characterised in detail by combination of different analytical techniques. Fractionation of one of the samples according to water‐solubility into four fractions revealed that a non‐statistical distribution of the substituents occurred for all fractions. Endoglucanase fragmentation of three samples was performed followed by analytical and preparative SEC. The multi‐detected analytical SEC proved samples of high degree of substitution up to 1.9 to be intensively degraded, supporting the proposed block‐like substitution pattern. The detailed investigation of soluble fragmentation products by preparative SEC, hydrolysis and anion exchange chromatography with pulsed amperometric detection revealed that all samples contain fragments of much higher DS values than the average DS of the starting material. On the other hand, high quantities of degradation products of low DS or almost no substitution occurred. Therefore, a structure can be proposed with segments of very high DS alternating with areas of limited substitution. The result clearly showed that the high substituted fragments were dominated by 2,3,6‐tri‐O‐CMG.

Structure analysis of 1,4-glucan derivatives

“…[27] Their results are reported in this issue in detail. [89] One limitation of the enzymic approach lies in the fact that the question whether a glucosidic linkage with a certain position in the sequence of a glucan derivative is attacked by an appropriate enzyme cannot be simply answered by "yes" or "no", but the rates may differ for some orders of magnitude [90] and do not only depend on the substitution pattern of the directly neighbored glucose units but also on the pattern of further ones as on the distance to the chain terminus, [91] since an oligomeric sequence is usually involved in the formation of the active complex.…”

Homogenous carboxymethylation of cellulose in the NaOH/urea aqueous solution

“…The CMC exhibits an unconventional distribution of ether groups and unconventional properties, i.e. the CMC showed a preferred substitution at position O-6, and a block-like distribution of the carboxymethyl groups along the polymer backbone [9][10][11]. In dimethyl sulfoxide/tetrabutylammonium fluoride (DMSO/TBAF) and in N-methylmorpholine-N-oxide (NMMNO) [12] CMC with DS values as high as 2.2 were accessible in a onestep synthesis.…”

Genome Structure ofBacillus cereustsu1 and Genes Involved in Cellulose Degradation and Poly-3-Hydroxybutyrate Synthesis

“…In order to understand the molecular basis for these biochemical activities and evaluate the biotechnological potential of this bacterial strain, we proceeded to analyze its genome structure and test its extracellular cellulase and PHB producing ability. Analysis of cellulose degradation activity using GPC and Congo red staining methods suggests that the bacteria can degrade cellulose into smaller molecular products, but the end-products of degradation were not identified [47][48][49]. Cellulose has been used as a low-cost substrate in PHAs fermentation studies.…”