title: Effect of hydrophobicity of acyl groups on the activity and stability of acylated thermolysin.
abstract: 1. Normal carboxylic acids of different hydrophobicities and similar chain lengths were prepared and used for the modification of amino groups of thermolysin (EC 3.4.24.4). They were 4,7,10,13-tetraoxatetradecanoic acid, 4,7,10-trioxatetradecanoic acid, 4,7-dioxatetradecanoic acid and 4-oxatetradecanoic acid. 2. The modified enzymes were isolated by gel filtration. They had 6--7 acyl groups per molecule. Acylation of amino groups with 4-oxatetradecanoic acid and tetradecanoic acid made the enzyme insoluble. 3. The most hydrophilic enzyme derivative had similar enzyme activity and higher heat resistance than the native enzyme. The most hydrophobic derivative showed lower Km (50%) and V (40%) values for proteinase activity and lower heat resistance than the former derivative. The trioxa-derivative had intermediate characteristics. The results are discussed with respect to effects on stability and activity of the enzyme.
mesh_terms: D000215:Acylation; D004355:Drug Stability; D005230:Fatty Acids, Nonesterified / Q000494:pharmacology*; D007700:Kinetics; D013329:Structure-Activity Relationship; D013820:Thermolysin / Q000378:metabolism
chemical_list: D005230:Fatty Acids, Nonesterified; D013820:Thermolysin