A Soluble, Folded Protein without Charged Amino Acid Residues

摘要: Charges are considered an integral part of protein structure and function, enhancing solubility providing specificity in molecular interactions. We wished to investigate whether charged amino acids indeed required for biogenesis a completely free titratable side chains can maintain solubility, stability, function. As model, we used cellulose-binding domain from Cellulomonas fimi, which, among proteins more than 100 acids, presently is the least Protein Data Bank, with total only four residues. find that shows surprising resilience toward extremes pH, demonstrating stability function (cellulose binding) pH range 2 11. To ask residues present were these properties this protein, altered them nontitratable ones. Remarkably, chargeless produced reasonably well Escherichia coli, retains its stable three-dimensional structu...