Hydrogenases immobilization

A critical factor for biotechnology application is the stability of the enzyme electrode. Hydrogenase immobilized into carbon filament material has high level of both operational and storage stability. Even after the half year of storage with periodical testing, the enzyme electrode preserved more than 50 % of its initial activity [9,10], Thus, it is possible to achieve appropriate stability of the enzyme electrode, suitable for hydrogen fuel cells development. 

Fig. 4. H2 photoevolution from ascorbate via P. laminosum PSI particles under different conditions of immobilization. The complete assay system contained 100 mM Mes-NaOH buffer, pH 7.0 75 mM sodium ascorbate 15 mM DTT 2 mM TMPD 1% (w/v) BSA PSI particles (30 pg Chi) 50 pi (saturating amount) of Clostridium pasteurianum hydrogenase and 12.5 pM Spirulina maxima Fd as electron mediator, (a) Conditions all components free (b) hydrogenase immobilized in Ca alginate according to Gisby and Hall (1980) (c) PSI particles immobilized in Ca alginate (d) hydrogenase and PSI coimmobilized in Ca alginate.

It is interesting to note that hydrogenase immobilized in a semiconductor exhibits a higher specific activity. In addition, the immobilization of the carrier significantly stabilizes the enzyme (Figure 19). 

Figure 18. Kinetic curves for the electrochemical isolation of hydrogen on the polymeric suspension electrode. (1) Hydrogenase immobilized into polymer (2) polymer suspension.

Diagram of hydrogenase molecules immobilized on an electrode surface... 

Berenson, J.A. and Benemann, J.R. 1976. Immobilization of hydrogenase and ferredoxins on glass beads. FEES Lett. 76, 105-107. 

Ruediger, O., Abad, J.M., Hatchikian, E.G., Fernandez, V.M., and de Lacey, A.L (2005) Oriented immobilization of Desulfovibrio gigas hydrogenase onto... 

The latter direction was initiated by Danielsson et al. (1979), who combined immobilized hydrogenase with a hydrogen gas-sensing MOSFET. Since the MOSFET requires a high operational temperature it was separated from the enzyme layer. Caras and Janata (1980) directly integrated the microelectronic sensor and the immobilized... 

The result of the screening of the immobilized artificial transfer hydrogenases is displayed as a fingerprint in Fig. 9. The most promising results of artificial transfer hydrogenases were subsequently reproduced using the purified non-immobilized... 

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