Purification and properties of the native form of the purple acid phosphatase from bovine spleen.
The purple acid phosphatase (PAP) from bovine spleen has been shown to exist as a single ca. 36-kDa polypeptide in intact spleen tissue. The previously isolated microheterogeneous complex of 15-kDa and 23- or 21-kDa subunits appears to arise from proteolytic cleavage of an exposed, highly variable loop in the polypeptide chain. Small amounts of a single polypeptide form, presumed to be the native form of the enzyme, have been obtained; this has permitted its optical and EPR spectra and fundamental kinetic properties to be determined. The most notable difference between the native and two-subunit forms of PAP is a ca. 3-fold higher enzymatic activity for the latter, which is due to a simple increase in Vmax. The two forms are very similar spectroscopically and chemically and appear to differ only in the loss of a highly antigenic ca. five amino acid segment of the polypeptide between positions 155 and 160 but not in NH2-terminal sequence or in carbohydrate content. Analysis of published sequence data suggests that the existence of an exposed highly antigenic loop at positions corresponding to 155-161 of the spleen PAP sequence is a relatively general feature of PAP's. Trypsin and chymotrypsin cleave both bovine spleen PAP and uteroferrin, apparently in this region, with significant enhancement of enzymatic activity.
Orlando
J L
JL
Department of Chemistry, University of Virginia, Charlottesville 22901.
Zirino
T
T
Quirk
B J
BJ
Averill
B A
BA
D000135:Acid Phosphatase / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D015153:Blotting, Western; D002241:Carbohydrates / Q000032:analysis; D002417:Cattle; D002942:Circular Dichroism; D004578:Electron Spin Resonance Spectroscopy; D010450:Endopeptidases / Q000494:pharmacology; D007527:Isoenzymes; D007700:Kinetics; D008667:Metalloproteins / Q000378:metabolism; D008969:Molecular Sequence Data; D008982:Molybdenum / Q000494:pharmacology; D010710:Phosphates / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D017421:Sequence Analysis; D013053:Spectrophotometry; D013154:Spleen / Q000201:enzymology*; D000071681:Tartrate-Resistant Acid Phosphatase
D000596:Amino Acids; D002241:Carbohydrates; D007527:Isoenzymes; D008667:Metalloproteins; D010710:Phosphates; D011480:Protease Inhibitors; C044659:molybdate; D008982:Molybdenum; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase; D010450:Endopeptidases