Abstract

Lipases are a family of enzymes which catalyze the hydrolysis of lipids and they exhibit esterase type activities such as phospholipase, lysophospholipase, cutinase and amidase. These enzymes have applications in detergent, the production of oil and fat, baked products, organic synthesis, hard surface cleaning, leather, paper, and cocoa butter. Lipases are versatile and have become a major source of industrial lipolytic enzymes. I performed a comparative analysis of protein sequences of well characterized fungal lipolytic enzymes from SWISS-PROT and developed a classification system to assist structural and functional characterization of newly identified putative lipase gene sequences. The distance-based UPGMA method was used for constructing the phylogenetic tree. Eight sequences of known secondary and tertiary structure were used to predict the secondary structure of similar sequences with unknown structure. Using sixteen different tools from SWISS-PROT and NPS@, the secondary structures of sequences with unknown 3-dimensional structures were predicted. The evolutionary based clustering of lipase protein sequences resulted in seven major families with the largest family being divided into five subfamilies and two single member branches. This analysis allowed us to: (i) perform a comparative study of well-characterized fungal lipases to develop a comprehensive classification system for fungal lipases, (ii) assess various protein secondary structure prediction tools to select suitable tool(s) for predicting secondary structures of lipases, (iii) predict structural features important for specific function of lipases such as residues forming the catalytic sites, disulfide bonds and salt bridges, and (iv) develop a framework to predict putative function and reaction conditions of newly identified lipase gene sequences.