Executive Summary : | Studying the external pressure effects on the biological molecular assemblies such as peptides provides deeper understanding of survival of life forms in deep biospheres on Earth and exoplanets, food sterilization industries, as well as has implications in bio-piezoelectricity. Peptides are complex molecular assemblies that form link between protein macromolecules and amino acid molecular crystals. There have been several high-pressure studies on proteins but mostly below 10 kbar (1 GPa) pressure and they could probe only the changes pertained to secondary structure of proteins such as conformational effects, and native folding defects. Moreover, these studies are phenomenological in the sense that they fail to assign the observed effects to molecular causes due to lack of sufficient knowledge of the behaviour of protein subunits (amino acids and peptides) under stress. A few recent reports on amino acid crystals indicate their extraordinary stability under stress, but there are hardly any high-pressure studies on peptides. This is in spite of recent findings that a few peptides exhibited piezoelectricity under external stress and their piezoelectric response is the highest among organic molecules. The origin of this bio-piezoelectricity which is rooted in the response of peptide structure and bonding to the stress needs thorough investigation. Computational approaches could be of help in this pursuit; however, they are hampered by the lack of structural data that is essential for the development of potential functions for modelling and refining the crystal structures. The present project is aimed at exploring this unchartered territory of probing the effect of mechanical pressure on the molecular packing, compressibility and conformations of biologically important peptides. Particular focus will be given to capturing the structural anisotropy and compressibility effects in covalently bonded peptide crystals such as cysteine-based peptides which are excellent candidates for bio-piezoelectricity. The outcome of this project will fill the knowledge gaps in the fundamental understanding of how complex biological macromolecules such as proteins and DNA behave under extreme pressure conditions and potentially throw some light on the molecular origin of intriguing bio-piezoelectricity in peptide structures. |