Amylose conformational transition

N 153 Analysis of Cooperative Conformational Transitions hi Cellulose and Amylose Triearbanilates"... 

J. M. Characterization of a thermally induced irreversible conformational transition of amylose tris(3,5-dimethylphenyl-carbamate) chiral stationary phase in enantioseparation of dihydropyrimidinone acid by quasi-equilibrated liquid chromatography and solid-state NMR, Anal. Chem., 2003, 75, 5877-5885. 

It has been shown that amylose in an aqueous solution exhibits considerable changes in intrinsic viscosity and optical rotation in the region of pH between 11 and I3, and this behavior has been interpreted in terms of the conformational change caused by increasing negative charges on the polymer chain (12-1 ). We can conclude that the changes in fluorescence intensity and polarization observed here are due to the same conformational transition of amylose. 

Physicochemical studies of other aliphatic, carboxylic esters of polysaccharides include (a) assessment of the gel-permeation properties of the series cellulose propionate-cellulose heptanoate, (b) dissolution of cellulose acetate phthalate, (c) monolayer properties of amylose acetate, and (d) melting and transition temperatures of the series amylose acetate-amylose hexanoate. Amylose acetate assumes a helical conformation at air-water interfaces and in oriented films, and the X-ray-analysis data for mannan acetate imply a threefold screw-axis... 

A study of the conformations of amylose and cellulose oligomers using vibrational spectroscopies has been reported. At the same conference, the use of FTIR (near, mid and far IR), and EXAFS, for spectroscopic characterization of mono- and disaccharides and coordination transition metal complexes was described. IR has been applied to characterize l,2 3,4-di-0-isopropylidene-6-0-triphenylstannylmethyl-a-D-galactopyranose. ... 

Marchessault, Sarko etal. [10, 11] have investigated the chiroptical properties of amylose xanthates extensively. The CD of amylose triacetate in trifluoroethanol shows, apart from the expected acetyl z -> tt transition at about 230 nm, an additional shortwave peak. This is again explained by assuming a helical conformation of the amylose chain. Dextran acetates and mycodextran acetates, on the other hand, do not show conformational effects. The considerable changes in the CD spectra of amylose triacetate films when the temperature increases from 30 to 190°C are particularly remarkable. As X-ray diffraction analysis shows, these effects are connected with crystallisation processes and transformation during annealing. 

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