Grey in the core of each hair. Melanin is also responsible for the color of the skin and of the eyes. There are only two types of pigment: dark (eumelanin) or light (phaeomelanin). Combined in various combinations, these pigments create all natural hair colors. Melanin itself is the product of a specialized cell, the melanocyte, which is found in each hair follicle, from which the hair grows. As hair grows, the melanocyte injects melanin into the hair cells, which contain the protein keratin and which makes up our hair, skin, and nails. As long as the melanocytes continue injecting melanin into
Protein design protein design programs vary greatly, they have to address four main modeling questions: What is the target structure of the design, what flexibility is allowed on the target structure, which sequences are included in the search, and which force field will be used to score sequences and structures. Protein function is heavily dependent on protein structure, and rational protein design uses this relationship to design function by designing proteins that have a target structure or fold. Thus, by definition, in rational protein design the target structure or ensemble of structures must be known beforehand. This contrasts with other forms of