Exopolygalacturonate lyase from a thermophilic Bacillus sp.

An endospore-forming bacterial strain that was isolated from the hot extrac t of su,oar beet and identified as a strain of Bacillus licheniformis excre tes an active 38-kDa exopolygalacturonate lyase. The enzyme was purified to homogeneity by ammonium sulfate precipitation, gel filtration, hydrophobic interaction chromatography, and ion-exchange chromatography. The pH optimu m of the enzyme was found to be 11.0 and the temperature optimum, 69 degree s C. Its activity is dependent on Ca2+; 100% activity was retained at 65 de grees C after 2 h. The N-terminal sequence was determined and found to cont ain the motif GFAALNGGTTGG in accordance with the motif G(aro)a(S-7x)TxGG i n other pectate lyases of the pelADE and pelBC families. 4,5-Unsaturated tr igalacturonate was released as the product by the action of the enzyme. (C) 1999 Elsevier Science Inc. All rights reserved.