| 1. |
- Buchert, Johanna, et al.
(författare)
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Effect of pulping and bleaching on pulp carbohydrates and technical properties.
- 1996
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Ingår i: Proceedings Int. Pulp Bleaching. ; , s. 39-42
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Konferensbidrag (refereegranskat)abstract
- Pulping and bleaching have a profound effect on the carbohydrate chem. of kraft pulps. The chem. structure of xylan is modified due to the conversion of methylglucuronic acid side groups to hexenuronic acid side groups. Pulping conditions strongly affect the amt. of hexenuronic acid present in the pulp and subsequently modified kraft pulps have different carboxyl group profiles as compared with conventionally cooked pulps. Due to its reactivity, hexenuronic acid is readily degraded when chlorine dioxide or ozone are used as bleaching chems. However, TCF-pulps bleached with peroxide and oxygen contain high amts. of hexenuronic acid. Thus, depending on the pulping and bleaching method, the quality and quantity of carboxylic acids in different types of pulps varies significantly. The differences in the uronic acid content are in turn reflected in the macroscale properties of the pulps, such as brightness stability.
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| 2. |
- Kotiranta, Pia, et al.
(författare)
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Adsorption and Activity of Trichoderma reesei Cellobiohydrolase I, Endoglucanase II, and the Corresponding Core Proteins on Steam Pretreated Willow
- 1999
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Ingår i: Applied Biochemistry and Biotechnology. - 1559-0291. ; 81:2, s. 81-90
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption and the hydrolytic action of purified cellulases of Trichoderma reesei, namely, cellobiohydrolase I (CBH I), endoglucanase II (EG II), and their core proteins, on steam-pretreated willow were compared. The two enzymes differed clearly in their adsorption and hydrolytic behavior. CBH I required the cellulose-binding domain (CBD) for efficient adsorption and hydrolysis, whereas EG II was able to adsorb to steam pretreated willow without its CBD. Absence of the CBD decreased the hydrolysis of cellulose by EG II, but the decrease was less pronounced than with CBH I. A linear relationship was observed between the amount of enzyme adsorbed and the degree of hydrolysis of cellulose only for CBH I. EG II and EG II core appeared to be able to hydrolyze only 1 to 2% of the substrate regardless of the amount of protein adsorbed.
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