Amino acid sequence at the allosteric site of sheep heart phosphofructokinase

Covalent modification of sheep heart phosphofructokinase with the affinity labeling reagent p-fluorosulfonyl[14C]benzoyl-5'-adenosine caused a loss of allosteric properties. This modification appears to occur at the binding site that is specific for the allosteric activators AMP, cAMP, and ADP (Mansour, T.E., and Colman, R.F. (1978) Biochem. Biophys. Res. Commun. 81, 1370-1376). In the current study, the site of modification has been demonstrated to be a lysine residue. A nonapeptide containing a covalently bound [14C]carboxybenzenesulfonyl group attached to alysine residue has been isolated following tryptic digestion. The amino acid sequence of the peptide is Asn-Phe-Ala-Thr-Lys-Met-Gly-Ala-Lys. The fifth residue in this sequence, lysine, contained the covalently bonded reagent.