Alkali modification of carrageenans. Part V. the iota-nu hybrid carrageenan from Eucheuma denticulatum and its cyclization to iota-carrageenan

A homogeneous iota/nu-hybrid cairageenan (71% iota- and 21% nu-) isolated from Eucheuma denticulatum was used as a model compound to study the cyclization reaction of α-D-galactose 2,6-disulfate units to 3,6-anhydro-α-D- galactose 2-sulfate. The rate of cyclization, at 70°C, of this carrageenan is a...

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Autores principales: Viana, A.G., Noseda, M.D., Duarte, M.E.R., Cerezo, A.S.
Formato: JOUR
Materias:
Alkaline treatment
Cyclization rate
Eucheuma denticulatum
Iota-carrageenan
Alkaline earth metals
Degradation
Enzyme kinetics
Ethanol
Seaweed
Sol-gels
Alkali metals
Eucheuma
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_01448617_v58_n4_p455_Viana
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_01448617_v58_n4_p455_Viana2023-10-03T14:59:44Z Alkali modification of carrageenans. Part V. the iota-nu hybrid carrageenan from Eucheuma denticulatum and its cyclization to iota-carrageenan Viana, A.G. Noseda, M.D. Duarte, M.E.R. Cerezo, A.S. Alkaline treatment Cyclization rate Eucheuma denticulatum Iota-carrageenan Alkaline earth metals Degradation Enzyme kinetics Ethanol Seaweed Sol-gels Alkaline treatment Cyclization rate Eucheuma denticulatum Iota-carrageenan Alkali metals Eucheuma A homogeneous iota/nu-hybrid cairageenan (71% iota- and 21% nu-) isolated from Eucheuma denticulatum was used as a model compound to study the cyclization reaction of α-D-galactose 2,6-disulfate units to 3,6-anhydro-α-D- galactose 2-sulfate. The rate of cyclization, at 70°C, of this carrageenan is about 50 times faster than that of a porphyran (non-sulfated β-D-galactose linked to α-L-galactose 6-sulfate) and 210 times faster when compared with a lambda-carrageenan (2-sulfated β-D-units linked to α-D-galactose 2,6-disulfate). The use of this model compound confirms the previous hypothesis of the accelerating effect of the β-o-4-sulfate group as well as suggests the influence of the 2-sulfate of the α-D-galactose units on the 4C1 → 1C4 chair forms interchange. The easy of cyclization indicates that to produce commercial iota-carrageenans milder alkaline treatments could be used, avoiding degradation and increasing the gel strength. © 2004 Elsevier Ltd. All rights reserved. Fil:Noseda, M.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Cerezo, A.S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_01448617_v58_n4_p455_Viana
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Alkaline treatment
Cyclization rate
Eucheuma denticulatum
Iota-carrageenan
Alkaline earth metals
Degradation
Enzyme kinetics
Ethanol
Seaweed
Sol-gels
Alkaline treatment
Cyclization rate
Eucheuma denticulatum
Iota-carrageenan
Alkali metals
Eucheuma
spellingShingle Alkaline treatment
Cyclization rate
Eucheuma denticulatum
Iota-carrageenan
Alkaline earth metals
Degradation
Enzyme kinetics
Ethanol
Seaweed
Sol-gels
Alkaline treatment
Cyclization rate
Eucheuma denticulatum
Iota-carrageenan
Alkali metals
Eucheuma
Viana, A.G.
Noseda, M.D.
Duarte, M.E.R.
Cerezo, A.S.
Alkali modification of carrageenans. Part V. the iota-nu hybrid carrageenan from Eucheuma denticulatum and its cyclization to iota-carrageenan
topic_facet Alkaline treatment
Cyclization rate
Eucheuma denticulatum
Iota-carrageenan
Alkaline earth metals
Degradation
Enzyme kinetics
Ethanol
Seaweed
Sol-gels
Alkaline treatment
Cyclization rate
Eucheuma denticulatum
Iota-carrageenan
Alkali metals
Eucheuma
description A homogeneous iota/nu-hybrid cairageenan (71% iota- and 21% nu-) isolated from Eucheuma denticulatum was used as a model compound to study the cyclization reaction of α-D-galactose 2,6-disulfate units to 3,6-anhydro-α-D- galactose 2-sulfate. The rate of cyclization, at 70°C, of this carrageenan is about 50 times faster than that of a porphyran (non-sulfated β-D-galactose linked to α-L-galactose 6-sulfate) and 210 times faster when compared with a lambda-carrageenan (2-sulfated β-D-units linked to α-D-galactose 2,6-disulfate). The use of this model compound confirms the previous hypothesis of the accelerating effect of the β-o-4-sulfate group as well as suggests the influence of the 2-sulfate of the α-D-galactose units on the 4C1 → 1C4 chair forms interchange. The easy of cyclization indicates that to produce commercial iota-carrageenans milder alkaline treatments could be used, avoiding degradation and increasing the gel strength. © 2004 Elsevier Ltd. All rights reserved.
format JOUR
author Viana, A.G.
Noseda, M.D.
Duarte, M.E.R.
Cerezo, A.S.
author_facet Viana, A.G.
Noseda, M.D.
Duarte, M.E.R.
Cerezo, A.S.
author_sort Viana, A.G.
title Alkali modification of carrageenans. Part V. the iota-nu hybrid carrageenan from Eucheuma denticulatum and its cyclization to iota-carrageenan
title_short Alkali modification of carrageenans. Part V. the iota-nu hybrid carrageenan from Eucheuma denticulatum and its cyclization to iota-carrageenan
title_full Alkali modification of carrageenans. Part V. the iota-nu hybrid carrageenan from Eucheuma denticulatum and its cyclization to iota-carrageenan
title_fullStr Alkali modification of carrageenans. Part V. the iota-nu hybrid carrageenan from Eucheuma denticulatum and its cyclization to iota-carrageenan
title_full_unstemmed Alkali modification of carrageenans. Part V. the iota-nu hybrid carrageenan from Eucheuma denticulatum and its cyclization to iota-carrageenan
title_sort alkali modification of carrageenans. part v. the iota-nu hybrid carrageenan from eucheuma denticulatum and its cyclization to iota-carrageenan
url http://hdl.handle.net/20.500.12110/paper_01448617_v58_n4_p455_Viana
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