Abstract: Disclosed herein are derivatives of atrial natriuretic peptides wherein the exocyclic N-terminal peptide segment is deleted and the two cysteinyl residues (at positions 105 and 121) of the natural sequence are replaced with a trivalent unit, --NHCH(CO--)--Q--X--Y--CH.sub.2 CH.sub.2 CO-- wherein Q is methylene, ethylene or CR'R" wherein R' and R" each independently is lower alkyl, X is oxy or thio, and Y is methylene or des-Y. The derivatives may be optionally substituted at various positions including positions 106, 107 and 124. The derivatives possess ANF-like activity and are indicated for treating hypertension and for treating pathological conditions resulting from an imbalance of body fluids and electrolytes.

Abstract: A resin and method for using the resin for solid phase peptide synthesis. The resin has a sulfoxide linkage, which is stalbe to strong acid conditions. The sulfoxide linkage can be reduced to a sulfide linkage, which allows cleavage of the peptide from the resin under mild acid conditions.