Study on Different Types of Structure Based Properties in Keratin and Collagen Types of Fibrous Proteins

During the process of protein folding, amino acid residues along the primary sequence interact with each other in a cooperative manner to form the stable native structure. To understand the mechanism of protein folding and stability, the knowledge about inter-residue interactions in protein structures is very helpful. In this comparative study, we have systematically analyzed aminoacid composition and various structure based properties of molecular interactions in two different classes of Fibrous proteins, Keratin and Collagen. Aminoacid composition, long range order, surrounding hydrophobicity, long range interactions, medium range interactions, accessible surface area, ionic interactions and hydrophobic interactions are the parameters used in the study. Structural based properties of Keratin and Collagen were statistically analyzed. The results obtained in this work highlight the difference in different structure based properties like long range order, surrounding hydrophobicity, long range interaction ratio, and medium range interaction ratio, average number of residues within 8A and accessible surface area of proteins, in Keratin and Collagen. Ionic interacting residues have higher value of surrounding hydrophobicity and higher value of neighbors within 8A, compared to ionic noninteracting residues. Accessible surface area of polar residue was found to be greater than nonpolar residues. There is marked difference in structural based properties of buried and non buried residues. Buried residues have higher value of surrounding hydrophobicity and higher value of neighbors within 8A, compared to non-buried residues. Hydrophobic interacting residues have higher value of surrounding hydrophobicity and higher value of neighbors within 8A, compared to hydrophobic noninteracting residues. Long range interactions are more prominent in hydrophobic interactions than in ionic interactions.