a) Chemical structure of amanitin, long-chain (Lc-SMPT) and short-chain (SPDP) cross-linkers. Fluorescence (b, d) and CD (c, e) spectra representing three states of pHLIP-amanitin conjugated via long-chain, SMPT, (b, c) and short-chain, SPDP, (d, e) cross-linkers are shown. State I corresponds to the construct in aqueous solution at pH 8, addition of liposomes results in formation of state II, and state III represents peptide inserted into lipid bilayer at pH 4. f) LogP values of amanitin and its conjugates with long- and short-chain cross-linkers are shown (where P is the octanol-water partition coefficient). d) The pH-dependence of pHLIP-SPDP-Am transition from the state II to the state III is shown.