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An a-l-rhamnosidase producing fungal strain has been isolated from decaying lemon fruit. The fungal strain has been identified as Aspergillus flavus. The a-l-rhamnosidase has been purified from the culture filtrate of the fungal strain using ultra filtration and cation exchange chromatography on carboxy methyl (CM) cellulose. The molecular mass of the purified enzyme determined by SDS-PAGE analysis was 41 kDa. The K m values of the enzyme using p-nitrophenyl-a-l-rhamnopyranoside and naringin as the substrates were 1.89 and 1.6 mm respectively. The pH and temperature optima of the enzyme were 11.0 and 50°C respectively. The effects of various chemical species present in grape fruit juice and wine on the activity of the enzyme have been determined.

A laccase has been purified from the liquid culture growth medium containing bagasse particles of Fomes durissimus. The method involved concentration of the culture filtrate by ultrafiltration and anion exchange chromatography on diethyl aminoethyl cellulose. The sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and native polyacrylamide gel electrophoresis both gave single protein band indicating that the enzyme preparation was pure. The molecular mass of the purified laccase determined from SDS-PAGE analysis was 75 kDa. Using 2,6-dimethoxyphenol as the substrate, the determined K (m) and k (cat) values of the laccase are 182 μM and 0.35 s(-1), respectively, giving a k (cat)/K (m) value of 1.92 × 10(3) M(-1) s(-1). The pH and temperature optimum were 4.0 and 35 °C, respectively. The purified laccase has yellow colour and does not show absorption band around 610 nm found in blue laccases. Moreover, it transformed methylbenzene to benzaldehyde in the absence of mediator molecules, property exhibited by yellow laccases.

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A laccase from the culture filtrate of white rot fungus Coriolopsis floccosa MTCC-1177 has been purified to homogeneity. The method involved concentration of the culture filtrate by ammonium sulphate precipitation and an anion exchange chromatography on diethylaminoethyl (DEAE) cellulose. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) as well as native polyacrylamide gel electrophoresis (native-PAGE) produced single protein bands indicating that the enzyme preparation was pure. Molecular mass of the enzyme determined from SDS-PAGE analysis was 64 kDa. Using 2,6-dimethoxyphenol (DMP), 2,2-[Azino-bis-(3-ethylbonzthiazoline-6-sulphonic acid (ABTS) diammonium salt and 4-hydroxy-3,5-dimethoxy benzaldehyde azine (syringaldazine) as the substrates, the K m , k cat and k cat /K m values of the laccase were found to be 112.5 μM, 5.16 s −1 , 4.60 × 10 4 M −1 s −1 , 58 μM, 5.16 s −1 , 8.90 × 10 4 M −1 s −1 and 100 μM, 5.16 s −1 , 5.16 × 10 4 M −1 s −1 , respectively. The pH and temperature optima were 5.0 • C and 40 • C, respectively. Activation energy for thermal denaturation of the enzyme was 36.6 kJ/mol/K. The enzyme was most stable at pH 4.0 when exposed for 1 h. The purified laccase has yellow colour and does not show absorption band around 610 nm found in blue laccases. The enzyme transforms toluene, 3-nitrotoluene and 4-chlorotoluene to benzaldehyde, 3-nitrobenzaldehyde and 4-chlorobenzaldehyde, respectively, in the absence of electron transfer mediators.