Lipase enzymes play an important role in lipid metabolism and are produced by a variety of species. Compared with animal, bacterial and fungal, little is known about plant lipases. Although lipases belong to many different protein families, they have the same architecture, the ?/?-hydrolase fold and a conserved active site signature, the Gly-Xaa-Ser-Xaa-Gly motif. Several studies on enzymatic activity and interfacial activation phenomenon of lipases confirm the presence of consensus sequence and a conserved domain. Lipases can be divided into two main groups: carboxylesterases (EC 3.1.1.1); 'true' lipases (EC 3.1.1.3), which differ in several biochemical features, which allow us to develop a database that regroups all 'true' lipase proprieties to establish relationship between structure and function. LIPABASE is a centralised resource database, which provides information about 'true' lipase from different species. It includes general, taxonomic, physicochemical and molecular data. Access to LIPABASE is free and available at http://www.lipabase-pfba-tun.org.

Lipases catalyze the hydrolysis of ester bonds in triacylglycerides, generating glycerol and free fatty acids. These enzymes are encoded by extremely complex gene families, and appear to fulfil many different biological functions. Although they are present in all types of organisms, available information on plant lipases is still very limited, as compared to their bacterial and animal counterparts. A full-length clone, BnLIP, encoding a putative lipase, has been isolated by PCR amplification of Brassica napus genomic DNA, with oligonucleotide primers derived from the sequence of an Arabidopsis thaliana homologue. The clone included an open reading frame of 1581 bp encoding a polypeptide of 526 amino acids, with a calculated molecular mass of 59.5 kDa. Analysis of the deduced protein sequence, sequence alignment with homologous proteins from related plant species, and a phylogenetic analysis revealed that the BnLIP protein belongs to the 'classical' GxSxG-motif lipase family. RT-PCR assays indicated that the BnLIP gene is expressed specifically, but only transiently, during seed germination: the lipase mRNA was not present at detectable levels in ungerminated seeds, was detected only three days after seed imbibition, but its levels decreased rapidly afterwards. No expression was observed in roots, stems or leaves of adult plants. This expression pattern suggests that BnLIP is one of the lipases involved in the hydrolysis of triacylglycerides stored in rapeseed seeds, ultimately providing nutrients and energy to sustain seedling growth until photosynthesis is activated.