Cu-SCys interactions are known to play a dominant role in determining the type 1 (T1) blue copper center with respect to both the electronic structure and electron transfer function. Despite this critical role must still be reviewed by mutagenesis studies without dramatic changes in the character of the T1 copper.
We here report the conserved Cys112 substitution in the amino acid homocysteine azurin with nonproteinogenic. Based on the electronic absorption, electron paramagnetic resonance, and x-ray absorption spectroscopy studies of structural delicate extended, this variant displays a typical type 1 copper site features.
Surprisingly, instead of increasing the strength of the Cu-sulfur interaction with the introduction of an extra methylene group, Cys112Hcy azurin showed a decrease in covalent interaction between SHcy and Cu (II) when compared with WT SCys-Cu (II) interaction.
This may be due to adjustments resulting geometric center of the copper ions move out of the trigonal plane defined by two histidine and one Hcy and closer to Met121. The structural changes resulting in an increase in abatement potential of 35 mV, consistent with low Cu-S Covalency.
These results indicate that Cu-SCys close interaction to be optimal in the original blue copper protein. It also demonstrates the power of using amino acids nonproteinogenic in addressing important issues in bioinorganic chemistry.
Reduced scytonemin isolated from Nostoc commune induces autophagic cell death in human T-lymphoid cell line Jurkat cells.
Nostoc commune is a blue-green algae benthic land that often form a slimy layer extended on the ground, up on the rocks and mud in aquatic environments. Scytonemin reduced (R-scy), isolated from N. commune Vaucher, has been shown to suppress the growth of Jurkat T-lymphoid human.
To highlight the underlying mechanisms of inhibition of the growth of Jurkat cells mediated by R-scy, we examined cell morphology, DNA fragmentation, and the light chain of the microtubule-associated protein 3 (LC3) changes in these cells. We observed several vacuoles and the conversion of LC3-I LC3-II R SCY-treated cells.
These results suggest that R-SCY inhibition of Jurkat induced cell growth is due to the induction of programmed cell death type II (PCD II autophagic cell death or autophagy). We also examined the underlying mechanisms R SCY-induced PCDII.
Cells treated with R-scy produces large amounts of reactive oxygen species (ROS), which leads to the induction of mitochondrial dysfunction. However, the removal of R-SCY ROS induced by treatment with N-acetyl-L-cysteine (NAC) substantially opposite of PCDII R-Scy-induced. Based on these results, we conclude that training plays a critical role in ROS R SCY-induced PCDII.