Biotechnol. Appl. Biochem. 19, 19-140[1994] (Printed in Great Britain ) |
Bovine pancreatic deoxyribonuclease F:isoelectric focusing,peptide mapping and primary structure |
Yung-Ming Chang, Shiming Lin, and Ta-Hsiu Liao |
Institute of Biochemistry , National Taiwan University College of Medicine, Taipei , Taiwan |
Abstract |
Dnase F is a minor isoform of bovine pancreatic DNAase which can be separated from the other isoforms ( Dnase A, B, C and D ) present in a commerical preparation by a preparative isoelectric focusing cell ( Rotofor:BioRad ).The ampholytes and other contaminating proteins present in DNAase preparations can be removed by chromatography on an affinity column ( Cibacron Blue 3 GA-agarose ) and a hydrophobio-interation column ( phenyl Sepharose CL-4 B ). The complete separation of DNAase F from the other iso-forms is demonstrated on a thin-layer isoelectric-focusing gel, DNAase F being the most basic ( PI 5.68 ). A procedure is described for trypetic peptide mapping by h. p. l. c. requiring only picomolar amounts of by map shows two peptide peaks not present in the DNAase A map, and the DNAase F map does not have a peak at the position where a C-terminal peptide of DNAase A is normally eluted. The amino acid compositions and sequences for the two new peptides suggest that Gly 240 in DNAase A is changed to Arg240 in DNAase F. |
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