The halophile protein database 2.0: A comprehensive resource of physico-chemical properties of halophilic proteins

Halophilic organisms are among the oldest microorganisms on earth which thrive in extreme saline environments through unique physiological and biochemical mechanisms. Halophiles are classified into extreme, moderate, and mild groups based on their salt tolerance. Proteins play a crucial role in their adaptation by undergoing structural modifications and cellular alterations and allowing them to maintain stability and functionality in high-saline conditions. To support research on halophilic adaptations, we have developed an advanced Halophile Protein Database 2.0 (HProtDB 2.0) which serves as a comprehensive resource for analyzing the physicochemical properties of halophilic proteins. This database provides extensive data on diverse physicochemical properties, including molecular weight, theoretical pI, amino acid composition, atomic composition, instability index, aliphatic index, extinction coefficients, estimated half-life, and the grand average of the hydropathicity index. These properties help researchers understand how halophilic proteins maintain their structure and function by influencing salt-ion interaction, solubility and protein folding. HProtDB 2.0 significantly expands the earlier version by increasing its dataset from 59,897 protein sequences (21 strains) to 777,979 protein sequences (54 strains) with enhanced precision in physicochemical properties. We developed R programs to compute physicochemical properties of halophilic proteins. Additionally, we designed the database using a three-tier web architecture, integrating HTML, CSS, and JavaScript for the front-end, PHP for server-side scripting, and MySQL for data storage. Researchers can access HProtDB 2.0 at: http://proteindb2.iari.res.in; http://webapp.cabgrid.res.in/proteindb2.0/. This database will serve as valuable tool for researchers seeking information on the characteristics and features of proteins adapted to salt conditions.