Evidence that the amino acid residue Ile121 is involved in arginine kinase activity and structural stability

The amino acid residue L113 is involved in arginine kinase activity and structural stability

“…Consistent with spectroscopic experiments, thermal inactivation result also implied that the mutations L113K, L113G and L113D affected the structural stability of the active site. This conclusion is consistent with the fact that amino acid residues in the linker may play key roles in the structural stability of AK [15,16,19,20].…”

“…1 and 2). Combined with the kinetic parameters, spectroscopic and protein folding results, one can deduce that the destruction of the C-and N-terminal domain interactions and incompact structure were responsible for the decreased substrate synergism, activity and structural stability, which were consistent with previous studies [20,21].…”

“…2B). Thus irreversibility might be caused by the formation of soluble non-native aggregation-prone intermediates [9][10][11][12]20,21]. Nevertheless, the transition curves of the mutant AKs were almost identical to that of WT AK at GdnHCl concentrations above 0.5 M, which suggested that mutations did not affect the MG ↔ U transitions.…”

“…The WT and mutant AKs fusion proteins were expressed in E. coli BL21 and purified as described previously [9][10][11][12][20][21][22]. The purity was checked by SDS-PAGE.…”

“…Interestingly, the side-chains of almost all hydrophobic residues are exposed to solvent, whereas those of L113 and I121 residues are buried and interact with the hydrophobic residues in the C-terminal domain. Our previous studies suggested that the amino acid residue I121 was involved in the AK activity and structural stability [20]. However, whether the amino acid residue L113 plays important roles in keeping AK activity and stability is still unclear.…”