The behavior of Phanerochaete chrysosporium cellobiose dehydrogenase on adsorption to crystalline and amorphous celluloses
1997
Samejima, M. | Ohkubo, T. | Igarashi, K. | Isogai, A. | Kuga, S. | Sugiyama, J. | Eriksson, K.E.L.
The adsorption of cellobiose dehydrogenase (CDH) to cellulose has been previously reported. However, the structural type of cellulose on to which CDH is adsorbed has not been investigated. In the present study we have compared the behaviour of CDH when it adsorbs on the highly crystalline cellulose microfibrils from Valonia macrophysa and on the completely amorphous cellulose prepared from a solution of Avicel in the SO2/amine system. The isotherms of CDH adsorption to both Valonia and amorphous celluloses fit well with the Langmuir adsorption theory. However, the maximum adsorption of CDH to the amorphous cellulose was much higher than that to Valonia cellulose. The location of CDH adsorbed on cellulose was revealed with colloidal-gold-tagged antibodies by transmission electron microscopy. By using this technique it was demonstrated that CDH adsorption to Valonia cellulose was limited to the amorphous regions attached to the crystalline microfibrils, whereas no CDH was adsorbed to the surface of the highly crystalline microfibrils. Furthermore, continuous monitoring of cellulase activity showed that limited amounts of structures susceptible to enzymic hydrolysis exist even on the surface of Valonia cellulose. From these observations, we conclude that amorphous regions of cellulose seem to the preferred sites of CDH adsorption, whereas CDH is not adsorbed to the surface of highly crystalline microfibrils.
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