Purification and molecular characterization of FAP, a feto-acinar protein associated with the differentiation of human pancreas.

摘要: Abstract This work describes the purification of FAP, a feto-acinar pancreatic protein associated with ontogenesis, differentiation, and transformation human exocrine pancreas. The was purified to homogeneity from juices patients pathology by two-step chromatographic procedure which consisted size exclusion on Sephacryl S-200 affinity heparin-Sepharose. final preparation gave single band at Mr 110,000 sodium dodecyl sulfate-polyacrylamide gel electrophoresis after Coomassie stain or autoradiography 125I-labeled protein. Immunodetection murine monoclonal antibody mAb J28 in nitrocellulose replicas demonstrated main component trace components 100,000-80,000 range. immunopattern identical that original crude secretion, therefore showing molecular characteristics protein, i.e. mass, microheterogeneity, immunoreactivity, were not altered along procedure. FAP identified as an acidic (isoelectric point 4.2-4.8) consisting polypeptide chain having no free SH residues. Analysis amino acid composition showed high proline content. Twenty-two residues N-terminal sequence determined. No significant homology between this peptide other proteins found following search NBRF-18 data bank. Sugar analysis presence mannose is consistent N-linked carbohydrate chains unusual ratio N-acetylgalactosamine suggesting many O-linked chains. Sequential deglycosylation neuraminidase, hexosaminidase, O-glycanase yield 58,000 that, relative mass 110,000, moiety accounts for least 47% its apparent electrophoresis.