Effects of carboxylation of the side chains on the order-disorder transition in aqueous solution of schizophyllan, a triple helical polysaccharide

Abstract

Schizophyllan and scleroglucan are water-soluble polysaccharides having repeating units consisting of three β-1,3-linked glucose residues in the main chain and a single β-1,6-linked glucose residue as the side chain. This polysaccharide dissolves as a triple helix in an aqueous solution and shows a cooperative order-disorder transition between the side chain and solvent molecules while retaining the triple helical conformation. Periodate and subsequent chlorite oxidations selectively modify the side chain glucose to provide the corresponding dicarboxylate units. Optical rotation measurements and differential scanning calorimetry were performed on carboxylated schizophyllan/scleroglucan ('sclerox') samples to investigate the effects of the degree of carboxylation on the order-disorder transition in deuterium oxide with 0.1M NaCl. The transition curves for the sclerox samples are strongly dependent on the degree of carboxylation. The modified side chains cannot take the ordered structure, resulting in a reduction of the transition enthalpy. The transition temperature for carboxylated schizophyllan becomes lowered and the transition curve broadens with increasing the degree of carboxylation. The permanent disordered units are included in a trimer by the carboxylation to inhibit a long sequence of the ordered units.

Conformation and cooperative order‐disorder transition in aqueous solutions of β‐1,3‐d‐glucan with different degree of branching varied by the Smith degradation

“…With increasing DB, T r was shifted to lower T , and Δ H r was decreased. These changes of the transition behavior well resemble those induced by the effects of carboxylation in our previous study on the carboxylated derivative (“sclerox”) . However, there are several differences in the DSC curves between these derivatives.…”

“…Such a linear cooperative system can be expressed by the LCT theory. Recently, we have extended the LCT theory to apply it to the carboxylated derivative (sclerox) to investigate the effects of the chemical modification on CODT . The degree of carboxylation (DS) was introduced into the theory to express the reduction of the number of unmodified side chain.…”

Cooperative Order–Disorder Transition of Carboxylated Schizophyllan in Water–Dimethylsulfoxide Mixtures

“…[18][19][20] Furthermore, subsequent chlorite oxidation can convert the dialdehyde side chain into the corresponsing dicarboxylates. [21][22][23][24][25][26][27][28] Carboxylated schizophyllan ('sclerox') is an ionic polysaccharide showing different solution properties from parent schizophyllan.…”

Applications of Photoinduced Phenomena in Supramolecularly Arranged Phthalocyanine Derivatives: A Perspective

“…In the same frame of biopolymers supramolecular assemblies for Pcs delivery in PDT applications, curdlan (CUR) based nanoparticles were even proposed with interesting results [160]. CUR ( Figure 29) is a β-(d)-glucan polymer able to spontaneously assemble in aqueous media into right-handed triple helices (t-CUR) [161]. The possibility to interconvert t-CUR into single strand CUR (s-CUR) in dimethyl sulfoxide (DMSO) was exploited to encapsulate a Pc derivative, creating CUR-Pc based nanoparticles of about 760 nm with a red-shifted Q band located at about 752 nm.…”