Stable analogs of bioactive peptides containing disulfide linkages

A cyclic peptide analog having the following general formula:

• wherein (AA1)k, (AA2)l, and (AA3)m are α-amino acids in the peptide and the bonds connecting (AA1)k, Q, (AA2)l, Z, and (AA3)m are conventional peptide bonds;
• k, l, and m are the number of α-amino acids and may range from 0 to 15 with the proviso that at least two of k, l, and m are greater the zero;
• W and X are —S— or —CHR1—, such that when W is —S—, then X is —CHR1— and when W is —CHR1—, then X is —S—;
• R1 is —(CH2)n—Y;
• n is from 0 to 10;
• Y is a reactive functional group capable of being coupled to a bifunctional effector molecule;
• and Q and Z may be the same or different and have the following general structure:
• wherein p may range from 0 to 3 and R2 is H, alkyl, aryl, hydroxyalkyl, alkoxyalkyl, and carboxyl wherein the carbon containing portions contain from 1 to 10 carbon atoms or the side chain portion of naturally occurring α-amino acids.