title: Performance evaluation of a silk protein-based matrix for the enzymatic conversion of tyrosine to L-DOPA.
abstract: L-DOPA (3,4-dihydroxyphenyl-L-alanine), one of the most important intermediates in the melanin biosynthesis pathway, is used for the treatment of Parkinson's disease. With a view of developing a cheaper and more effective method for the bioconversion of tyrosine to L-DOPA, the potential and performance of a novel fibrous matrix prepared from Bombyx mori silk protein fibroin were evaluated for the immobilization of tyrosinase. Cross-linkage between fibroin and tyrosinase using glutaraldehyde was evident from Fourier transform infra red spectroscopy. Maximum product formation occurred when 1000 U enzyme was immobilized on 20 mg fibroin. The optimum conditions for maximal L-DOPA production using immobilized tyrosinase were 40 degrees C and pH 5.5, conditions that caused a 50% loss of free enzyme activity. Immobilized tyrosinase also showed to have a higher degree of stability during storage and it retained 80% of its original activity after repeated reuses. The efficiency of this immobilized tyrosinase system to produce L-DOPA was high, as evident from a high effectiveness factor, between 0.7 and 0.8, thereby making this method feasible for the large-scale production of L-DOPA.
authors.affiliation: Department of Biotechnology, Indian Institute of Technology, Kharagpur, India.
authors.forename: Chitrangada
authors.initials: C
authors.lastname: Acharya
authors.forename: Veerendra
authors.initials: V
authors.lastname: Kumar
authors.forename: Ramkrishna
authors.initials: R
authors.lastname: Sen
authors.forename: Subhas C
authors.initials: SC
authors.lastname: Kundu
mesh_terms: D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D005349:Fibroins / Q000737:chemistry; D005976:Glutaral / Q000737:chemistry; D007980:Levodopa / Q000378:metabolism*; D014442:Monophenol Monooxygenase / Q000737:chemistry / Q000378:metabolism*; D047011:Silk / Q000378:metabolism*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D004800:Enzymes, Immobilized; D047011:Silk; D014443:Tyrosine; D007980:Levodopa; D005349:Fibroins; D014442:Monophenol Monooxygenase; D005976:Glutaral