A conformationally-constrained kinked peptide includes: a conformationally-constraining portion and a kinked portion linked to the conformationally-constraining portion that conformationally constrains the kinked portion, the kinked portion comprising an endosomal-disrupting peptide. The peptide can include a peptide sequence of one of SEQ ID NOs: 1, 5-38, or 40-69. The conformationally-constrained kinked portion can be a majority portion or minority of the peptide. The peptide can include one of Formulae 1-1C, wherein: CC-Peptide includes a peptide that conformationally constrains the ED-KP Peptide independently includes natural, unnatural, essential or non-essential aromatic, aliphatic, or other amino acids having L or D configuration ED-KP includes an endosomal-disrupting kinked peptide Xaa, Xaa1, and Xaa2 are independently one or more natural or non-natural amino acids, essential amino acids, or non-essential amino acids, or derivatives of amino acids having L or D configuration L1 and L2 are independently linkers and n1, n2, n3, and n4 are independently 0-50.
