The
protein patterns of cytosols from normal human pancreas and
pancreatic carcinoma were studied by a two-dimensional separation technique using high-performance liquid chromatography followed by isoelectric focusing on
polyacrylamide gels and visualization of the focused
proteins by
Coomassie Blue staining. Almost identical
protein patterns were obtained for 20 different specimens from normal pancreas, whereas quite different
protein patterns were found in 12 samples of
pancreatic carcinoma. A major
protein in normal pancreatic cytosol, not identical to any macromolecule previously tested as a marker for pancreatic function, was selected for further studies. The
protein was not found in specimens of
pancreatic carcinoma. It was purified by a single step chromatofocusing procedure, focused at pH 6.9, and moved as one single band in
sodium dodecyl sulfate-
polyacrylamide gel electrophoresis with an apparent molecular weight of 44,500 daltons. Total
amino acid analysis revealed a high concentration of
glutamic acid,
leucine, and
lysine. The purified
protein had no
amylase activity or
lipase immunoactivity. It constituted approximately 2% of the total normal pancreatic cytosol
protein. Later immunological studies have shown the
protein to be highly specific for normal human pancreas, indicating a possible future use as a marker for pancreatic cell damage.