Research Article

Computational Exploration on the Formation and Stability of S-Nitrosothiols: Biological Implications in Nitric Oxide Storage/Scavenging

Gurusamy Muneeswaran1,3,*, Kaliappan Muthukumar2, Chandran Karunakaran3,*
1Division of Chemistry, Faculty of Science and Humanities, AAA College of Engineering and Technology (Autonomous), Amathur-626005, Sivakasi, Tamil Nadu, India
2Applied Materials, Sunnyvale, United States
3Biomedical Research Laboratory, Department of Chemistry, VHNSN College (Autonomous), India
Corresponding Author: Gurusamy Muneeswaran, Department of Chemistry, Faculty of Science and Humanities, AAA College of Engineering and Technology (Autonomous), Amathur-626005, Sivakasi, Tamil Nadu, India.
📘 Volume 1, Issue 1 📄 Pages: 1-8 📅 September 30, 2026 🔗 DOI: Pending 🏷️ Research Article

Article Information

Article Type: Research Article
Submitted: September 06, 2026
Accepted: September 22, 2026
Published: September 30, 2026
Pages: 1-8
DOI: Pending
Language: English
License: CC BY 4.0

Abstract

Nitric oxide (NO) is involved in post translational modification of cysteine (cys) residues under both physiological and pathological conditions. NO formation and S-nitrosation of various proteins observed during ischemia thus alter its functions. S-nitrosothiols have been reported to be protective against cardiac reperfusion injury. In order to understand the mechanism of formation and stability of S-nitrosothiols, the adduct formation reaction of NO with cys, homocysteine (Hcys), cysteamine (cysA) and N-acetylcysteine (NAC) have been investigated using 6-31G (d, p) basis set at HF method. The relative activation energies are 50.83, 404.56, 405.99, and 455.57 Kcal/mol for cys-NO, cysA-NO, NAC-NO and Hcys respectively indicates that cys-NO adduct has the least energy conformer whereas Hcys-NO has the highest energy state. The S-N bond lengths after the adduct formation are 1.8323, 1.8309, 1.8328 and 2.5267 Å for cys-NO, cysA-NO, NAC-NO and Hcys-NO, respectively and are consistent with a sulfur-nitrogen single bond in agreement with the experimental report. The relative rotational energy of CSNO dihedral angle determined for cys-NO adduct is reasonably in agreement with the already reported similar kind of adduct. Among the biologically important investigated thiols, cys-NO adduct is easily formed and very stable when compared to other cys substituted adducts. These findings shed further insight into complexity to researchers understanding of NO biology and provide valuable suggestions for the design of new nitroso adducts as medicinal therapies.

Keywords

Cysteine Nitrosothiols Transition state Mulliken charge Activation energy Nitric Oxide S-Nitrosothiols Homocysteine Cysteamine N-Acetylcysteine

Cite

Citation: Gurusamy Muneeswaran, Kaliappan Muthukumar and Chandran Karunakaran (2026) Computational Exploration on the Formation and Stability of S-Nitrosothiols: Biological Implications in Nitric Oxide Storage/Scavenging. Epistora J. Biomed. Sci. & Res. 1(1), 1-08. Article EJBSR-2026-103