Table 1.

Binding affinities of the phosphotyrosine mimetic amino acids and peptides 1, 3, 10, 12, and 14–17 to protein tyrosine phosphatase PTP1B calculated from enzyme inhibition assays.

Compound	K I in μM[a]
1	1555±183[b]
3	61±8[c]
10	[f]
12	52±7[d]
14	90±10[c]
15	24±4,[b] 25±4,[c] 21±3[d]
16	74±13,[e] 33±5,[c] 19±3[d]
17	[f]

[a] Assays were performed in triplicate with DiFMUP as a substrate (see Supporting Information part for raw data). Enzyme concentration was 1.5 nM, substrate concentration 67 μM, identical with the experimentally determined K _M value of the substrate. IC₅₀ values were converted into the corresponding K _I values applying the Cheng‐Prusoff equation (with [S]=K _M this results in IC₅₀/2=K_I ). [b] 0 % DMSO, [c] 2.5 %, [d] 5 % DMSO, [e] 2.5 %, stock diluted in buffer, [f] visible precipitate.