title: A facile enzymatic synthesis of geranyl propionate by physically adsorbed Candida rugosa lipase onto multi-walled carbon nanotubes.
abstract: In view of several disadvantages as well as adverse effects associated with the use of chemical processes for producing esters, alternative techniques such as the utilization of enzymes on multi-walled carbon nanotubes (MWCNTs), have been suggested. In this study, the oxidative MWCNTs prepared using a mixture of HNO3 and H2SO4 (1:3 v/v) were used as a supportive material for the immobilization of Candida rugosa lipase (CRL) through physical adsorption process. The resulting CRL-MWCNTs biocatalysts were utilized for synthesizing geranyl propionate, an important ester for flavoring agent as well as in fragrances. Enzymatic esterification of geraniol with propionic acid was carried out using heptane as a solvent and the efficiency of CRL-MWCNTs as a biocatalyst was compared with the free CRL, considering the incubation time, temperature, molar ratio of acid:alcohol, presence of desiccant as well as its reusability. It was found that the CRL-MWCNTs resulted in a 2-fold improvement in the percentage of conversion of geranyl propionate when compared with the free CRL, demonstrating the highest yield of geranyl propionate at 6h at 55°C, molar ratio acid: alcohol of 1:5 and with the presence of 1.0g desiccant. It was evident that the CRL-MWCNTs biocatalyst could be reused for up to 6 times before a 50% reduction in catalytic efficiency was observed. Hence, it appears that the facile physical adsorption of CRL onto F-MWCNTs has improved the activity and stability of CRL as well as served as an alternative method for the synthesis of geranyl propionate.
authors.affiliation: Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia.
authors.forename: Nur Royhaila
authors.initials: NR
authors.lastname: Mohamad
authors.affiliation: Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia. Electronic address: noraziah@kimia.fs.utm.my.
authors.forename: Nor Aziah
authors.initials: NA
authors.lastname: Buang
authors.affiliation: Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia.
authors.forename: Naji Arafat
authors.initials: NA
authors.lastname: Mahat
authors.affiliation: Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia.
authors.forename: Yen Yen
authors.initials: YY
authors.lastname: Lok
authors.affiliation: Department of Biotechnology and Medical Engineering, Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia.
authors.forename: Fahrul
authors.initials: F
authors.lastname: Huyop
authors.affiliation: Pharmaceutical and Medicinal Chemistry Department, Pharmaceutical and Drug Industries Research Division, National Research Centre, Dokki, Cairo 12311, Egypt.
authors.forename: Hassan Y
authors.initials: HY
authors.lastname: Aboul-Enein
authors.affiliation: Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia. Electronic address: roswanira@kimia.fs.utm.my.
authors.forename: Roswanira
authors.initials: R
authors.lastname: Abdul Wahab
mesh_terms: D000327:Adsorption; D055162:Biocatalysis; D001709:Biotechnology; D002175:Candida / Q000201:enzymology*; D003890:Desiccation; D004800:Enzymes, Immobilized / Q000378:metabolism; D004951:Esterification; D005656:Fungal Proteins / Q000378:metabolism*; D008049:Lipase / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D037742:Nanotubes, Carbon / Q000648:ultrastructure; D011422:Propionates / Q000378:metabolism*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D037742:Nanotubes, Carbon; D011422:Propionates; D008049:Lipase
keywords: Candida rugosa lipase; Carbon nanotubes; Esterification; Geraniol; Geranyl propionate; Immobilization