Abstract: Reflectin proteins are intrinsically disordered proteins (IDPs) found in the light manipulating systems of cephalopods. These proteins are known to possess appealing optical and electrical properties, such as optical reflectivity and proton conductivity. Reflectin has the potential to become optically and electronically tunable; however, the molecular structure of reflectin has yet to be determined. Previous studies demonstrated the concatemers of subdomains from reflectin 1b domain 4 in native squid reflectin protein have the same light scattering properties as detected in the full full-length reflectin protein. Applying recombinant protein techniques, we purified the reflectin 4Ax4 protein which consists of four linked copies of subdomain 4A. We determined the leucine, tryptophan, and threonine amino acids are in an ordered state by solid solid-state nuclear magnetic resonance. Knowing these ordered amino acids is possibly the key to understanding reflectin’s natural optical and electrical properties. Understanding the link between reflectin’s structure and optical response is essential to making the next generation of tunable photonic materials based on natural resources.