Peptides and compounds that bind to a receptor

A compound that binds to a thrombopoietin receptor, wherein said compound comprises

• X9 X8 G X1 X2 X3 X4 X5 X6 X7
• where X1 is P;
• X2 is T;
• X3 is L;
• X4 is R;
• X5 is Q;
• X6 is selected from the group consisting of W (Trp), L-Trp, D-Trp, L-1-NaI, D-1-NaI, L-2-NaI, D-2-NaI, L-(Benzothienyl)-alanine, DL-5-Me-Trp, DL-1-Me-Trp, DL-6-F-Trp, DL-5-F-Trp, DL-5-Br-Trp and L-Tic;
• X7 is L;
• X8 is E;
• X9 is I.

A method of activating a thrombopoietin receptor in a cell, comprising contacting said cell with an effective amount of a compound which comprises:

• X9 X8 G X1 X2 X3 X4 X5 X6 X7
• where X1 is P;
• X2 is T;
• X3 is L;
• X4 is R;
• X5 is Q;
• X6 is selected from the group consisting of W (Trp), L-Trp, D-Trp, L-1-NaI, D-1-NaI, L-2-NaI, D-2-NaI, L-(Benzothienyl)-alanine, DL-5-Me-Trp, DL-1-Me-Trp, DL-6-F-Trp, DL-5-F-Trp, DL-5-Br-Trp and L-Tic;
• X7 is L;
• X8 is E;
• X9 is I.

A method of treating a patient suffering from thrombocytopenia, comprising administering to said patient a therapeutically effective dose of a compound which comprises:

• X9 X8 G X1 X2 X3 X4 X5 X6 X7
• where X1 is P;
• X2 is T;
• X3 is L;
• X4 is R;
• X5 is Q;
• X6 is selected from the group consisting of W (Trp), L-Trp, D-Trp, L-1-NaI, D-1-NaI, L-2-NaI, D-2-NaI, L-(Benzothienyl)-alanine, DL-5-Me-Trp, DL-1-Me-Trp, DL-6-F-Trp, DL-5-F-Trp, DL-5-Br-Trp and L-Tic;
• X7 is L;
• X8 is E;
• X9 is I.

A method of prophylactically treating a patient at risk of thrombocytopenia, comprising administering to said patient a prophylactically effective amount of a compound:

• X9 X8 G X1 X2 X3 X4 X5 X6 X7
• where X1 is P;
• X2 is T;
• X3 is L;
• X4 is R;
• X5 is Q;
• X6 is selected from the group consisting of W (Trp), L-Trp, D-Trp, L-1-NaI, D-1-NaI, L-2-NaI, D-2-NaI, L-(Benzothienyl)-alanine, DL-5-Me-Trp, DL-1-Me-Trp, DL-6-F-Trp, DL-5-F-Trp, DL-5-Br-Trp and L-Tic;
• X7 is L;
• X8 is E;
• I9 is I.

A compound that binds to thrombopoietin receptor, said compound having:

• (i) a molecular weight of less than about 8000 daltons, and (ii) a binding affinity to thrombopoietin receptor as expressed by an IC50 of no more than about 100 μM, wherein said compound comprises the following sequence of amino acids:
• X9 X8 G X1 X2 X3 X4 X5 X6 X7
• where X1 is P;
• X2 is T;
• X3 is L;
• X4 is R;
• X5 is Q;
• X6 is selected from the group consisting of W (Trp), L-Trp, D-Trp, L-1-NaI, D-1-NaI, L-2-NaI, D-2-NaI, L-(Benzothienyl)-alanine, DL-5-Me-Trp, DL-1-Me-Trp, DL-6-F-Trp, DL-5-F-Trp, DL-5-Br-Trp and L-Tic;
• X7 is L;
• X8 is E;
• I9 is I.