Determination of the Number-Average Degree of Polymerization of Cellodextrins and Cellulose with Application to Enzymatic Hydrolysis
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- 作者：Y.-H. Percival Zhang and Lee R. Lynd
- 刊名：Biomacromolecules
- 出版年：2005
- 出版时间：May 2005
- 年：2005
- 卷：6
- 期：3
- 页码：1510 - 1515
- 全文大小：112K
- 年卷期：v.6,no.3(May 2005)
- ISSN：1526-4602
文摘
A rapid and accurate method for determining the number-average degree of polymerization (DPn) wasestablished for insoluble cellulose and soluble cellodextrins as the ratio of glucosyl monomer concentrationdetermined by the phenol-sulfuric acid method divided by the reducing-end concentration determined bya modified 2,2'-bicinchoninate (BCA) method. The modified BCA method, featuring incubation at 75 
Cfor 30 min, did not result in 
-glucosidic bond cleavage, whereas substantial cleavage was observed athigher temperature. Solubilization of insoluble cellulose in cold phosphoric acid prior to measurement ofthe reducing-end concentration by the BCA method was found not to be necessary for several model cellulosessuch as microcrystalline cellulose, but such solubilization was required for large fibers of cellulose such asWhatman No. 1 filter paper. The phenol-sulfuric acid method can be used for measuring the glucosylmonomer concentration of soluble cellodextrins, and also for insoluble cellulose if preceded by a liquefactionstep. Standard deviations of 
2% were obtained for both reducing and glucosyl monomer determinationand of 3% for overall determination of DP. By use of the reported method, hydrolysis of phosphoricacid-swollen cellulose (PASC) by the Trichoderma reesei cellulase system was shown to result in a rapiddecrease in DP as hydrolysis proceeded. By contrast, the DP of Avicel remained nearly constant duringhydrolysis. The specific enzymatic cellulose hydrolysis rate is 100-fold higher for PASC as compared toAvicel.
Cfor 30 min, did not result in -glucosidic bond cleavage, whereas substantial cleavage was observed athigher temperature. Solubilization of insoluble cellulose in cold phosphoric acid prior to measurement ofthe reducing-end concentration by the BCA method was found not to be necessary for several model cellulosessuch as microcrystalline cellulose, but such solubilization was required for large fibers of cellulose such asWhatman No. 1 filter paper. The phenol-sulfuric acid method can be used for measuring the glucosylmonomer concentration of soluble cellodextrins, and also for insoluble cellulose if preceded by a liquefactionstep. Standard deviations of 2% were obtained for both reducing and glucosyl monomer determinationand of 3% for overall determination of DP. By use of the reported method, hydrolysis of phosphoricacid-swollen cellulose (PASC) by the Trichoderma reesei cellulase system was shown to result in a rapiddecrease in DP as hydrolysis proceeded. By contrast, the DP of Avicel remained nearly constant duringhydrolysis. The specific enzymatic cellulose hydrolysis rate is 100-fold higher for PASC as compared toAvicel.