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Evidence for Conformational Transitions in Amylose1

 

作者: Masakuni Tako,   Susumu Hizukuri,  

 

期刊: Journal of Carbohydrate Chemistry  (Taylor Available online 1995)
卷期: Volume 14, issue 4-5  

页码: 613-622

 

ISSN:0732-8303

 

年代: 1995

 

DOI:10.1080/07328309508005362

 

出版商: Taylor & Francis Group

 

数据来源: Taylor

 

摘要:

The flow behavior, dynamic viscoelasticity, and optical rotation of an aqueous solution of amylose were measured using a rheogoniometer and a polarimeter, respectively. The amylose solutions showed shear-thinning behavior at a concentration of 1.2%, but plastic behavior above 1.4% at 25 °C. With increasing amylose concentrations the viscosity decreased rapidly with increasing temperature from 20 to 25, 30, and 35 °C. These latter temperatures are estimated to be first transition temperatures at the respective concentrations. Viscosities were scarcely changed until temperatures reached 70, 90, and 90 °C, which were estimated to be second transition temperatures, for 1.2, 1.4, and 1.6% solutions, respectively. Gelation occurred at a concentration of 1.2% at room temperature (2.5 °C). The dynamic modulus of amylose increased gradually with increasing temperature from 20 to 30 °C and kept a constant value until the temperature reached 65, 75, and 80 °C for 1.0, 1.2 and 1.4% solutions, respectively, which were estimated to be transition temperatures, then dynamic modulus decreased rapidly. The dynamic modulus of amylose stayed at a very low value with addition of urea (4.0 M). The optical rotation of amylose solution (1.0%) increased a little with deceasing temperature up to 25 °C, then it increased rapidly with further decrease of the temperature. Possible mode of intra- and intermolecular hydrogen bonding within and between amylose molecules were proposed.

 

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