title: L-Ascorbate, a strong inducer of L-dopa (3,4-dihydroxy-L-phenylalanine) production from pre-grown mycelia of Aspergillus oryzae NRRL-1560.
abstract: The inductive effect of L-ascorbate on the microbiological production of L-dopa (3,4-dihydroxy-L-phenylalanine) from Aspergillus oryzae NRRL-1560 was investigated. All biochemical reactions were performed aerobically using mould mycelia as a source of enzyme tyrosinase and acetate buffer (pH 3.0) as an extractant. L-Tyrosine as a substrate was added at a level of 2.5 mg/ml. Maximal L-dopa production (1.876 mg/ml) was achieved when L-ascorbate (5.0 mg/ml) was added 6 min after the initiation of the biochemical reaction at 50 degrees C, consuming 2.144 mg/ml L-tyrosine. The performance of fuzzy-logic control of the reaction was found to be highly promising for improvement of the substrate conversion rate (~80%). After optimizing the reaction conditions, particularly the addition of L-ascorbate, an increase in L-dopa yield of 22.96% was achieved compared with the control (without ascorbate addition) when the process variables, namely buffer pH, L-tyrosine concentration and reaction temperature, were further identified using a two-factorial Plackett-Burman design.
authors.affiliation: Department of Chemistry, GC University Lahore, Katchehry Road, Lahore, 54600 Pakistan. majied.irfana@yahoo.com
authors.forename: Irfana
authors.initials: I
authors.lastname: Mariam
authors.forename: Sikander
authors.initials: S
authors.lastname: Ali
authors.forename: Asia
authors.initials: A
authors.lastname: Rehman
authors.lastname: Ikram-Ul-Haq
mesh_terms: D001205:Ascorbic Acid / Q000494:pharmacology*; D001236:Aspergillus oryzae / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D017143:Fuzzy Logic; D007980:Levodopa / Q000096:biosynthesis*; D014443:Tyrosine / Q000378:metabolism
chemical_list: D014443:Tyrosine; D007980:Levodopa; D001205:Ascorbic Acid