The solid-state molecular structure of the S-nitroso derivative of l-cysteine ethyl ester hydrochloride

Abstract

Nitrosation of protein sulfhydryl groups to form thionitrites (S-nitrosothiols) has been reported to be important in the biochemistry of nitric oxide. Such S-nitrosation of protein thiol residues has been shown to alter the function of some proteins. In this brief communication, we report the X-ray crystal structure of S-nitroso-L-cysteine ethyl ester hydrochloride. Two rotamers with respect to the NCCS moiety are present in the crystal: the major rotamer is in the gauche+ conformation, and the minor rotamer is in the rare anti (trans, antiperiplanar) conformation for a cysteinyl compound. Importantly, the CSNO groups for both rotamers are in the syn (cis, synperiplanar) form. To the best of our knowledge, this is the first reported high-resolution solid-state structure of an S-nitroso derivative of a cysteine or cysteinyl-containing compound.

S-Nitrosylation-induced Conformational Change in Blackfin Tuna Myoglobin

“…A C-S-N-O dihedral angle of Ϫ69.5°was observed, despite the fact that no steric clashes would occur if the group were present with a cis dihedral angle of 0°. Additionally, the S-N and N-O bond lengths deviated substantially from those observed in small molecule crystal structures (33) and predicted from high level calculations (39), suggesting that it may also be a more reduced sulfur-bound nitrogen oxide species.…”

“…1), with C-S-N-O dihedral angles of ϳ0°. Interestingly, two conformations of this group were similarly observed in the small molecule crystal structure of S-nitroso-L-cysteine ethyl ester (33), implying that some degree of static disorder may be an intrinsic feature of this chemical substituent. Quantum mechanical calculations demonstrate that two energy minima exist for the C-S-N-O dihedral angle, at 0 and 180°, due to delocalization of the N ϭ O electrons over the S-N bond (a phenomenon that may be familiar from the planar peptide bond within the backbone of proteins).…”

“…1C). Geometric restraints for the refinement of the Cys-10 S-NO group were generated based on a small molecule crystal structure of S-nitroso-L-cysteine ethyl ester (33). For the ferrous nitrosyl myoglobin structure, no restraints were placed on the Fe-NO bond lengths or angles during the final stages of refinement.…”

The Structure and Conformation of (CH3)3CSNO

“…also contains molecules with an anti conformation ( τ (CSNO)=175.7°),11 whereas the primary S ‐nitrosocaptopril thionitrite adopts a syn conformation ( τ (CSNO)=0.7°) in its crystals 12. 13 A few other crystal structures have been reported 14. However, it becomes apparent that other than steric effects, in particular electronic properties of the group R determine the conformational preference 15.…”

Conformational Properties of Ethyl- and 2,2,2-Trifluoroethyl Thionitrites, (CX3CH2SNO, X = H and F)

“…17 On the other hand, the syn conformation [τ(CS-NO)= 0.7°] was observed in the crystal structure of Snitrosocaptopril, which can deliver NO and captopril under physiological conditions, with S-N and N=O bond lengths of 1.766 and 1.206 Å, respectively. 18,19 Few other experimentally determined structures can be found in the literature. [19][20][21] In general it was assumed that -mainly due to sterical reasons -tertiary thionitrites prefer the anti conformation, whereas the syn form is adopted by primary derivatives.…”