The synthesis of an ATP-γ-Peptidyl ester as a potential probe of c-AMP-dependent protein kinases

Increasing the Kinase Specificity of K252a by Protein Surface Recognition

“…These results suggest that molecules that combine a potent active-site-directed inhibitor with a miniature protein specificity element could represent viable tools to selectively explore kinase function. [21][22][23][24][25][26][27] Our design of miniature protein 1 began with the structure of the catalytic subunit of PKA in complex with the active portion of PKI (PKI 5-24 , Figure 1A), a molecule that selectively recognizes PKA and inhibits its function. In this complex, the N-terminal R-helix of PKI 5-24 (residues 5-13) nestles in a shallow hydrophobic groove outside the substratebinding site of PKA with contacts from F10 and perhaps T6 and Y7 (residues in green in Figure 1B).…”

“…44 Our results suggest that molecules such as 1-K252a that embody elements of protein surface recognition, in addition to bisubstrate inhibition, 26 could represent a general strategy to selectively explore kinase function. [21][22][23][24][25][26][45][46][47]…”

“…The indolocarbazole natural product K252a is a potent, active-site-directed inhibitor of many tyrosine and serine/threonine kinases 16-19 and a common starting point for the discovery of specific kinase inhibitors. , Miniature protein 1 recognizes PKA selectively with an affinity that rivals that of PKI and, in the context of 1-K252a , leads to a dramatic increase in kinase specificity. These results suggest that molecules that combine a potent active-site-directed inhibitor with a miniature protein specificity element could represent viable tools to selectively explore kinase function. −

1 (A) Structure of the catalytic subunit of PKA (purple) in complex with PKI 5 - 24 28 (black). (B) Strategy for miniature protein design.

…”

Synthesis of oligophosphopeptides and related ATP .gamma.-peptide esters as probes for cAMP-dependent protein kinase

“…H-Ser-Leu-Gly-NHMe-HCl (6b) A 98 0.45 (A) glass Boc-Arg(N02)-Ala-OBu-t (7) B6 94 0.48 (E), 0.83 (A) powder'® Ac-Leu-Arg2-Ala-Ser-Leu-Gly-NHMe-2HOAc (lb) F 100 0.22 (A), 0.57 H) 8.5 (9) powder'® "Satisfactory elemental analysis (±0.4 for C, H, and N). 6THF reaction solvent.…”

“…Boc-Arg(N02)-Arg(N02)-Ala-OBu-f (9) and Boc-Leu-Arg-(N02)-Arg(N02)-Ala-0Bu-t (11) were also selectively deprotected by using this procedure, referred to as method D (Table III). The cleavage product of 9, Arg(N02)-Arg(N02)-Ala-0Bu-t (10), required several additional extractions with EtOAc to obtain suf- (mp, °C) ppm Z-Ser[0P(0)(0Ph)2]-Leu-Gly-0Me (16a) G 94 0.61 (B), 0.48 (I)…”