CORM-3 Reactivity toward Proteins: The Crystal Structure of a Ru(II) Dicarbonyl−Lysozyme Complex

Abstract

CORM-3, [fac-Ru(CO)(3)Cl(κ(2)-H(2)NCH(2)CO(2))], is a well-known carbon monoxide releasing molecule (CORM) capable of delivering CO in vivo. Herein we show for the first time that the interactions of CORM-3 with proteins result in the loss of a chloride ion, glycinate, and one CO ligand. The rapid formation of stable adducts between the protein and the remaining cis-Ru(II)(CO)(2) fragments was confirmed by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES), Liquid-Chromatography Mass Spectrometry (LC-MS), Infrared Spectroscopy (IR), and X-ray crystallography. Three Ru coordination sites are observed in the structure of hen egg white lysozyme crystals soaked with CORM-3. The site with highest Ru occupancy (80%) shows a fac-[(His15)Ru(CO)(2)(H(2)O)(3)] structure.

Analysis of the Bacterial Response to Ru(CO)3Cl(Glycinate) (CORM-3) and the Inactivated Compound Identifies the Role Played by the Ruthenium Compound and Reveals Sulfur-Containing Species as a Major Target of CORM-3 Action

“…Although previous work has shown that iCORM-3 has much less effect than CORM-3 on biological material (8,17,34,37), very little has been done to elucidate bacterial viability with, and specific responses to, iCORM-3. The data presented herein show that iCORM-3 (made via incubation of CORM-3 in PBS) has virtually no effect on the growth of E. coli, whereas at the same concentration, CORM-3 readily inhibits growth (Fig.…”

“…This process is thought to allow CORM-3 to release the labile CO, which escapes into the gas phase upon bubbling, leaving a CO-depleted iCORM-3 compound in solution (8). However, mounting literature suggests that CORM-3 is unable to release large quantities of CO under these conditions; rather, the carbonyl compound is altered forming a stable molecule that releases CO with a much slower rate (13,28,37). This inactivation process could produce a very slow CO-releasing tricarbonyl complex (22) or a dicarbonyl compound, which is formed via the release of CO 2 from CORM-3 (37).…”

“…However, mounting literature suggests that CORM-3 is unable to release large quantities of CO under these conditions; rather, the carbonyl compound is altered forming a stable molecule that releases CO with a much slower rate (13,28,37). This inactivation process could produce a very slow CO-releasing tricarbonyl complex (22) or a dicarbonyl compound, which is formed via the release of CO 2 from CORM-3 (37). Whichever form is made, we can be sure that this inactivated compound is made directly from the active CORM-3 molecule and is therefore likely to mimic the compound present in vivo after CO has been released.…”

“…Despite the ambiguity of its chemical structure, the iCORM-3 compound has been used in studies as a non-CO releasing control for CORM-3 (8,17,34,37) to test the reactivity of the Ru-compound when all labile CO has been removed. In all cases, iCORM-3 was shown to be much less reactive than the CO-RM.…”

Fast infrared spectroscopy of protein dynamics: advancing sensitivity and selectivity

“…In fact the original purpose for which amino acids containing an azide group has been designed was "click" chemistry, and consequently one may also add metal-carbonyl complexes with even stronger C≡O bands to it in a post-translational coupling step as a second alternative [48]. Finally, Re-carbonyl or Ru-carbonyl complexes have been bound selectively to histidines [30,[56][57][58].…”