Abstract

ATP diphosphohydrolase from S. mansoni tegument was characterized as a 63-kDa protein with two isoforms possessing different isoelectric points. Antibodies against potato apyrase and Toxoplasma gondii nucleoside triphosphatase react with the 63-kDa protein, thus revealing the presence of common epitopes and suggesting that S. mansoni ATP diphosphohydrolase belongs to the family of apyrases. This is a new family of nucleotide-splitting enzymes so far unnoticed which became evident after sequencing 59 amino acids from potato apyrase. The novel potato apyrase sequences obtained have considerable homologies to eight sequences recently deposited in the data bank, including that of T. gondii nucleoside triphosphatase. The new family of apyrases contain a conserved motif (I/V)(V/M/I)(I/L/F/C)DAGS(S/T) near the amino terminal and three other regions showing four to six conserved amino acids.