不同化学组成的壳聚糖的高碘酸盐氧化反应

Periodate oxidation of chitosans with different chemical compositions.

作者信息

Vold Inger M N, Christensen Bjørn E

机构信息

Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology, Norwegian University of Science and Technology, Sem Saelands vei 6/8, N-7491 Trondheim, Norway.

出版信息

Carbohydr Res. 2005 Mar 21;340(4):679-84. doi: 10.1016/j.carres.2005.01.002.

DOI:10.1016/j.carres.2005.01.002

PMID:15721340

Abstract

Periodate oxidation of chitosans with different chemical compositions were investigated by determining the consumption of periodate consumed, and the amount of ammonia and formaldehyde liberated during the reaction. Oxidised chitosans were further characterised by size-exclusion chromatography with online multi-angle light scattering (SEC-MALLS) to obtain the molecular weight distributions, and by elemental analysis to obtain the N/C ratio. Chitosans became only partially oxidised by periodate, reaching degrees of oxidation around 0.5, when oxidising with excess periodate. Overconsumption of periodate is attributed to the extensive depolymerisation, which occurs concomitantly with the oxidation, thereby exposing novel reducing and non-reducing ends which consume additional periodate. Both the rate and extent of overoxidation, and the rate of depolymerisation decreased with increasing F(A). A chitosan-specific degradation mechanism is probably involved in the depolymerisation in addition to the general free-radical-mediated degradation.

摘要

通过测定高碘酸盐的消耗量以及反应过程中释放的氨和甲醛的量，研究了不同化学组成的壳聚糖的高碘酸盐氧化反应。通过在线多角度光散射尺寸排阻色谱法（SEC-MALLS）对氧化壳聚糖进行进一步表征以获得分子量分布，并通过元素分析获得N/C比。当用过量的高碘酸盐氧化时，壳聚糖仅被高碘酸盐部分氧化，氧化度达到约0.5。高碘酸盐的过度消耗归因于广泛的解聚，这与氧化同时发生，从而暴露出消耗额外高碘酸盐的新的还原端和非还原端。随着F(A)的增加，过氧化的速率和程度以及解聚的速率均降低。除了一般的自由基介导的降解外，壳聚糖特异性降解机制可能参与了解聚过程。