Bi-substrate analogue ligands for affinity chromatography of protein kinases

Novel affinity ligands, consisting of ATP-resembling part coupled with specificity determining peptide fragment, were proposed for purification of protein kinases. Following this approach affinity sorbents based on two closely similar ligands AdoC-Aoc-Arg4-Lys and AdoC-Aoc-Arg4-NH(CH2)6NH2, where AdoC stands for adenosine-5'-carboxylic acid and Aoc for amino-octanoic acid, were synthesized and tested for purification of recombinant protein kinase A catalytic subunit directly from crude cell extract. Elution of the enzyme with MgATP as well as L-arginine yielded homogeneous protein kinase A preparation in a single purification step. Also protein kinase A from pig heart homogenate was selectively isolated using MgATP as eluting agent. Protein kinase with acidic specificity determinant (CK2) as well as other proteins possessing nucleotide binding site (L-type pyruvate kinase) or sites for wide variety of different ligands (bovine serum albumin) did not bind to the column, pointing to high selectivity of the bi-functional binding mode of the affinity ligand.