This study is about how peptide sequences can control the assembly and growth of gold nanomaterials. Two cysteine-containing sequences, YYCYY and glutathione (GSH), have been newly identified as assembly motifs to control the resulting two-dimensional (2D) morphology. Cysteine interacts with gold ions and the gold surface to initiate nucleation and control growth. YYCYY forms a flat, 2D, gold-decorated film and GSH results in twisted, petal-like structures. By conducting a comparative study of these two sequences, the important role of peptide folding in the gold atom assembly process is investigated.