DSIP crosses the blood-brain barrier freely an unusual property for a peptide of its size via a non-competitive, non-saturable passive mechanism whose physicochemical determinants (lipophilicity, charge, molecular weight, and protein-binding) are now well characterised
Steiger A, Guldner J, Hemmeter U, Rothe B, Wiedemann K, Holsboer F
However, the affinity towards the diphenolic substrate L -DOPA, which features a carboxyl group, increased ( K m = 4.2 mM) in contrast to dopamine, which showed a decreased affinity ( K m = 2.36 mM, Table 2)
Allowing researchers to isolate satiety effects from glucose homeostasis pathways
But if I wanted to, I could use smaller doses