To explore whether atom extensions to 842NN could increase their H1R affinities, DWBEL from the 842NN parent were performed by: restricting its random co-evolutions to its terminal -COOH atoms (Figure , right-up red circle, at 842NN), targeting the 842NN H1R cavity and increasing to <650 g/mol their molecular weight preferences. The resulting 1588 children predicted maximal ~ 0.009 nM affinity for lead top-child 413NN2 additionally showing a linearized ring and 4 Carbon and 2 Nitrogen terminal atoms (Figure , right-down red circles, at 413NN2). Many other atom variations were predicted within similar scaffolds for the 1588 842NN-derived children.