Physical and Chemical Properties of the Lipase of Thermophilic Fungus Humicola lanuginose S-38

Abstract

Some physical and chemical properties of the extracellular lipase from the thermophilic fungus, Humicola lanuginosa S-38, were investigated. The results were as follows: Sedimentation coefficient was 2.4×10^-13 (cm•g/sec•dyne); diffusion coefficient was 8.8×10^-7(cm²/sec); and frictional coefficient was 1.22. Molecular weight was 27, 500±500 and α-helix content was 18.9%. The number of amino acid residues contained in 1 mole of protein of Humicola lipase was 224. Sugar and lipid were not detected. The effect of calcium ion and denaturing reagents, such as urea, sodium dodecyl sulfate and dithiothreitol, on the thermostability of Humicola lipase was examined. It was concluded that the thermostability of Humicola lipase was not influenced by protective cofactors but was attributable to the enzyme itself. Some properties of enzyme structure which were concerned with the thermostability of Humicola lipase are also discussed.