An acidic beta-1,3 glucanase from potato tubers appears to be patatin

A beta -1,3-glucanase (GLU-40) (EC 3.2.1.39) was isolated from potato tuber s (Solanum tuberosum L. cv. Huinkul). Purification was performed by anion e xchange chromatography and by affinity chromatography. The following result s suggested that the enzyme was, in fact, patatin: a) the molecular mass of the purified enzyme was 40 kDa, the same as that of the patatin; b) the pI of the purified enzyme was approximately 4-4.5, which corresponds to that of patatin; and c) the amino-terminal amino acid sequence and the sequence of internal peptides of the purified enzyme showed a high degree of homolog y to that of patatin. Patatin is known as a storage protein of the potato t uber and it has been shown to have esterase activity. However, other enzyma tic activities and the function(s) of patatin are unknown. Our results sugg est a new, still unknown physiological role for patatin. (C) 2001 Editions scientifiques et medicales Elsevier SAS.