Pharmaceutically acceptable salts of polypeptides and methods of inhibiting the interaction between psd-95 and n-methyl-d-aspartic acid receptor (nmdar)

A pharmaceutically acceptable salt of a peptide, wherein the peptide comprises the amino acid sequence YEKLLDTEI (SEQ ID NO:1) or a functional variant thereof, wherein the functional variant is a variant only having one or more conservative substitutions in YEKLLDTEI (SEQ ID NO:1), wherein the conservative substitution is selected from the group consisting of a substitution between D and E, a substitution among L, V and I, and a substitution between T and S, wherein the peptide or the functional variant thereof is capable of binding to the PSD-95/Discs-large/ZO-1 1/2 domain (PDZ1/2) domain of postsynaptic density 95 protein (PSD-95) and inhibiting the interaction between PSD-95 and N-methyl-D-aspartic acid receptor (NMDAR), and wherein the salt is an acetate.