To better understand the relation between structure and function of complex natural heme proteins, we have designed and synthesized de novo simplified versions called maquettes. Furthermore, we have assembled organized monolayers of these heme protein maquettes onto silanized quartz to mon define their structural and functional properties and to take the first step in constructing robust devices that exploit biological chemistry. First, two di-alpha-helical peptides, alpha(2), were designed and synthesized to self-assemble into a four-helix bundle [alpha(2)](2). The assembly has a well-developed hydrophobic interior and coordinates iron protoporphyrin IX (heme) by bis-histidine ligation. The chemisorption of these synthetic hemoproteins onto silanized quartz was achieved by reacting disulfide bridges in the loop region of each cl with thiols immobilized at the surface, Self-assembled monolayers of synthetic hemoproteins were characterized by UV/vis spectroscopy. UV absorption of the tryptophan reveals the presence of peptides on the substrate, and circular dichroism (CD) seems to indicate that the axes of the alpha-helices are oriented at a angle less than 45 degrees relative to the substrate. The construction of monolayers of hemoproteins was successfully achieved in two different ways : (1) Hemes were incorporated after the apoproteins were self-assembled onto the silanized quartz substrate. This process led to bis-histidyl ligated hemes and to physisorbed porphyrins inside or at the surface of the monolayer, Physisorbed hemes were removed by immersion of the film in NaCl and imidazole solutions, (2) Heme-containing holoproteins were prepared in solutions before self-assembly onto silanized quartz. Linear dichroism of the heme bis-ligated to the histidines showed an average tilt angle of the porphyrin plane of 40 degrees relative to the surface, consistent with an inclination of the whole assembly on the substrate suggested by CD measurements. Monolayers of hemoproteins after reduction. bind CO by displacing one of the histidines. Their absorption spectra are remarkably similar to the ones reported for the cytochrome c(3).