Normalized lipophilicity and solvent accessible surface area (SASA) values for natural and modified amino acids, assuming maximal side-chain exposure.

aScaled parameter = (raw parameters+3.800)/6.457, where the value of 3.800 is the raw parameter value for logP(Arg+) and the value of 6.457 is the sum of the absolute values of two raw parameters, logP(Arg+) and logP(Ile).The normalized parameter values are equal to the scaled parameter values minus the scaled parameter value for logP(Gly).bThe SASA of amino acid (X) is the exposed solvent-accessible surface area of its side chain in the tripeptide Gly-X-Gly, assuming that ψ = φ = 180°.Cα was not considered to be part of the side chain of X.cOxidized cysteine (Cys) has 50% of the lipophilicity of cystine (Css), i.e. the oxidized dimer of cysteine.logP(Cys) = [logP(Css)]/2, where logP(Css) = logP(CH2-S-S-CH2).dlog(Gly) = log(H).eAt pH = 7.4, histidine exists in protonated (His+) and unprotonated forms (His0) with mole fractions of 11.2% and 88.8%, respectively.logP(His) = logP(His+)⋅mole fraction (His+)+logP(His0)⋅mole fraction (His0).flog(Pro) = log(CH2-CH2-CH2-N).gAck: acetylated lysine.hCdr+: modified arginine with 1,2-cyclohexanedione.iKyw: kynurenine, a metabolite of tryptophan.jMee: methyl-δ-glutamate.