Saccharification of native and degraded cotton cellulose and commercial microcrystalline cellulose by <i>Trichoderma viride</i> cellobiohydrolase I

The degree of polymerization of samples of acid degraded cotton cellulose has no appreciable influence on the saccharification by cellobiohydrolase I from Trichoderma viride. The increase in the number of cellulose molecule ends, achieved by a 30-fold decrease in molecular weight, does not produce the effect which could be expected for a pure end-wise mode of action of this exoglucanase. Microcrystalline celluloses saccharified by the same enzyme yield considerably more reducing sugars than cotton cellulose, either with a similar degree of polymerization or one of about 7000. It appears, therefore, that the difference in the susceptibility of the commercial substrates is not a consequence of their low degree of polymerization.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Dilute acid-hydrolized cotton cellulose : An electron diffraction study

A comparative morphological investigation by electron diffraction analysis was carried out on samples of cotton cellulose from different stages of dilute-acid-catalysed hydrolytic degradation reactions. Within the range from $\overline {DP_n }$ 13000 (native material) to 500 only a gentle decrease of the relative crystallinity was observed. For $\overline {DP_n }$ below 500 the crystallinity decreases much faster, together with a simultaneous marked increase in paracrystalline lattice distortion and the show up of crystallographic evidence for a new cellulose phase which became better defined as degradation proceeded. A clearly defined parallel can be established between the different kinetic stages of the degradation reaction and the degree-of-polymerization dependence of the morphological features. The resulting evidence is at odds with the traditionally held views about the effects of acid hydrolysis of cellulose on its morphological fine structure.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Dilute acid-hydrolized cotton cellulose : An electron diffraction study

A comparative morphological investigation by electron diffraction analysis was carried out on samples of cotton cellulose from different stages of dilute-acid-catalysed hydrolytic degradation reactions. Within the range from $\overline {DP_n }$ 13000 (native material) to 500 only a gentle decrease of the relative crystallinity was observed. For $\overline {DP_n }$ below 500 the crystallinity decreases much faster, together with a simultaneous marked increase in paracrystalline lattice distortion and the show up of crystallographic evidence for a new cellulose phase which became better defined as degradation proceeded. A clearly defined parallel can be established between the different kinetic stages of the degradation reaction and the degree-of-polymerization dependence of the morphological features. The resulting evidence is at odds with the traditionally held views about the effects of acid hydrolysis of cellulose on its morphological fine structure.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Saccharification of native and degraded cotton cellulose and commercial microcrystalline cellulose by <i>Trichoderma viride</i> cellobiohydrolase I

The degree of polymerization of samples of acid degraded cotton cellulose has no appreciable influence on the saccharification by cellobiohydrolase I from Trichoderma viride. The increase in the number of cellulose molecule ends, achieved by a 30-fold decrease in molecular weight, does not produce the effect which could be expected for a pure end-wise mode of action of this exoglucanase. Microcrystalline celluloses saccharified by the same enzyme yield considerably more reducing sugars than cotton cellulose, either with a similar degree of polymerization or one of about 7000. It appears, therefore, that the difference in the susceptibility of the commercial substrates is not a consequence of their low degree of polymerization.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada