Synthesis and characterization of ordered mesoporous silicas for the immobilization of formate dehydrogenase (FDH)

Simultaneous CO2 reduction and NADH regeneration using formate and glycerol dehydrogenase enzymes co-immobilized on modified natural zeolite

“…Also in our previous works, with FDH on glyoxyl or amino mordenite and glyoxyl silica, an increase in optimal temperature was not obtained. 15,16 Concerning the behavior of co-immobilized enzymes, the co-presence of FDH and GlyDH on the same support seems to increase the activity at a lower temperature, FDH is most active at 60 °C while GlyDH is at 50 °C, and the optimal temperature is the same obtained for the enzymes separately immobilized. As far as pH is concerned, the two free enzymes are characterized by significantly different optimal values, around 7 for FDH and up to 10 for GlyDH.…”

“…39 In our previous works, FDH on glyoxyl silica showed a retained activity of 10–14%, while with FDH on glyoxyl or amino natural zeolite a retained activity from 4 to 40% was obtained. 15,16 Approximating the shape of the two enzymes with a sphere, 40 a diameter of 5.54 nm and 8.99 nm is obtained, starting with molecular weights of 74 kDa, 41 and 31.6 kDa, 42 respectively for FDH and GlyDH. Moreover, GlyDH is a multimeric enzyme composed of 8 subunits, 42 therefore the loss of activity during immobilization is likely due to the dissociation of its units and their desorption from the support.…”

“…The immobilization process is a critical point because the environment in which the reactions occur significantly affects the global performance of the enzyme: the confinement into materials with specific morphologies and the co-presence of other enzymes in the surroundings are two conditions that can modify the behavior of the enzyme. 15 Among all the possible materials, inorganic porous supports, such as silica and zeolites, present good features and are very suitable for enzyme immobilization, although in some cases it is necessary to change the zeolites' morphology due to their reduced pore size. 15–17 Natural zeolites such as clinoptilolite can be used as a valid alternative to synthetic ones due to their low cost.…”

“…15 Among all the possible materials, inorganic porous supports, such as silica and zeolites, present good features and are very suitable for enzyme immobilization, although in some cases it is necessary to change the zeolites' morphology due to their reduced pore size. 15–17 Natural zeolites such as clinoptilolite can be used as a valid alternative to synthetic ones due to their low cost. Furthermore, they have the advantage of being materials that are widespread in different parts of the world.…”

Mechano-chemical and biological energetics of immobilized enzymes onto functionalized polymers and their applications

“…The immobilized enzyme exhibited higher immobilization yield, thermal stability but the low yield of formic acid was obtained. As the enzymatic reduction reaction of CO 2 is reversible, so formed formic acid is converted back into CO 2 which results in a low yield of formic acid [ 169 ]. To upscale the CO 2 conversion experiment various challenges need to be overcome such as various impurities present in flue gas including nitrous oxide and sulfur trioxide that may affect the enzyme performance [ 170 , 171 ].…”