Thermolabile alkaline phosphatase from Northern shrimp (Pandalus borealis): protein and cDNA sequence analyses

Sequence analysis of short fragments resulting from trypsin digestion of th e thermolabile shrimp alkaline phosphatase (SAP) from Northern shrimp Panda lus borealis formed the basis for amplification of its encoding cDNA. The p redicted protein sequence was recognized as containing the consensus alkali ne phosphatase motif comprising the active site of this protein family. Pro tein sequence homology searches identified several eukaryote alkaline phosp hatases with which the 475-amino acid SAP polypeptide revealed shares 45% a mino;acid sequence identity. Residues for potential metal binding seem to b e conserved in these proteins. The predicted 54-kDa molecular mass of SAP i s smaller than previously reported, but is consistent with our recent SDS-P AGE analysis of the native protein. Compared to its homologs, the shrimp en zyme has a surplus of negatively charged amino acids, while the relative nu mber of prolines is lower and the frequency of aromatic residues is higher than in mesophilic counterparts. (C) 2001 Elsevier Science Inc. All rights reserved.