Degree Type

Dissertation

Date of Award

1984

Degree Name

Doctor of Philosophy

Department

Biochemistry, Biophysics and Molecular Biology

Abstract

Aqueous amylodextrins form helical complexes with alcohol, halogenated hydrocarbons, and triiodide known as V-complexes. With the formation of these complexes, the ('13)C-nuclear magnetic resonance (n.m.r.) signals of carbons 1 and 4 are shifted substantially downfield due to rotations about the glycosidic bond necessary to form the helical conformation. ('13)C-N.m.r. studies with amylodextrin, (alpha)-methyl D-glucoside, and (alpha)-methyl maltoside complexes suggest a complexing mechanism in which pyranose ring strain, induced by binding of the complexing agent, is relieved by rotations about the glycosidic bonds.;Retrograded amylodextrin, gives ('1)H and ('13)C n.m.r. spectra identical to those of dissolved amylodextrin. These results, along with X-ray diffraction studies, indicate that retrograded amylodextrin, exists as a double helix, which (a) has a reticulate structure leading to an isoluble aggregate, and (b) because of hydration of the chains retains the conformation of dissolved amylodextrin in solution.;Human salivary (HSA), porcine pancreatic (PPA) and Bacillus subtilis (BSA) (alpha)-amylases have been used to study the structures of amylose-V complexes and retrograded amylose. These (alpha)-amylases hydrolyze the amorphous folding areas on the surfaces of the lamella of packed helices with the formation of resistant amylodextrin fragments. PPA or HSA was used to hydrolyze n-butyl and t-butyl alcohol and (alpha)-naphthol amylose-V complexes to yield resistant fragments of degree of polymerization (d.p.) 75 (+OR-) 4, 90 (+OR-) 3, and 123 (+OR-) 2), respectively. These d.p. values correspond to six, seven, and nine glucose residues per turn, for a folding length of 10 nm.;Acid hydrolysis of retrograded amylose gave resistant fragments with an average d.p. of 32. HSA and PPA hydrolyses each gave resistant fragments of d.p. 43 and BSA gave a fragment of d.p. 50. These slightly larger resistant fragments of the (alpha)-amylase hydrolyses result from the (alpha)-amylase leaving "stubs" on the ends of the resistant fragments. The lengths of the stubs are dependent on the sizes of the binding sites of the individual (alpha)-amylases. Hydrolysis of amylose-V complexes and retrograded amylose by (alpha)-amylases or acid may be used as a new method of preparing amylodextrins of different sizes, with a relatively narrow size distribution.

DOI

https://doi.org/10.31274/rtd-180813-5942

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Jay-lin Jane

Language

en

Proquest ID

AAI8423714

File Format

application/pdf

File Size

117 pages

Included in

Biochemistry Commons

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