The ability of salts to stabilize proteins or intracellularly correlates with the Hofmeister series of ions.

Numerous studies have been conducted on the ability of salts to stabilize proteins using purified proteins demonstrating the fact that the ability of salts to stabilize proteins correlates with the Hofmeister series of ions. Using the well characterized bacterial aqueous cytosolic β-galactosidase and catechol 2,3-dioxygenase enzymes, we demonstrated that salts can stabilize proteins or intracellularly as well and that the ability of salts to stabilize these two proteins intracellularly also correlates with the Hofmeister series of ions. NaSO and NaHPO were very effective at stabilizing both proteins, followed by NaCl, NHCl and (NH)HPO, while NHCHCO, (NH)SO and NaCHCO did not stabilize either of the proteins.

Nonfunctional Missense Mutants in Two Well Characterized Cytosolic Enzymes Reveal Important Information About Protein Structure and Function.

The isolation and characterization of 42 unique nonfunctional missense mutants in the bacterial cytosolic β-galactosidase and catechol 2,3-dioxygenase enzymes allowed us to examine some of the basic general trends regarding protein structure and function. A total of 6 out of the 42, or 14.29% of the missense mutants were in α-helices, 17 out of the 42, or 40.

The Promiscuous sumA Missense Suppressor from Salmonella enterica Has an Intriguing Mechanism of Action.

While most missense suppressors have very narrow specificities and only suppress the allele against which they were isolated, the sumA missense suppressor from Salmonella enterica serovar Typhimurium is a promiscuous or broad-acting missense suppressor that suppresses numerous missense mutants. The sumA missense suppressor was identified as a glyV tRNA Gly3(GAU/C) missense suppressor that can recognize GAU or GAC aspartic acid codons and insert a glycine amino acid instead of aspartic acid. In addition to rescuing missense mutants caused by glycine to aspartic acid changes as expected, sumA could also rescue a number of other missense mutants as well by changing a neighboring (contacting) aspartic acid to glycine, which compensated for the other amino acid change.