Abstract

In recent years, much attention has been focused on the chemistry and biology of nitric oxide due to the discovery that it plays a key role in a wide variety of physiological processes. It has been suggested that S-nitrosothiols may be directly involved in many of the biological functions of nitric oxide and that they play a role in nitric oxide storage, transport and delivery. The mechanism of nitric oxide transfer from an S-nitrosothiol to a low-molecular-weight thiol or to a protein-based thiol is still unknown. In this work, evidence for a mechanism in which traces of copper play a role in nitric oxide transfer between thiols is presented. A new synthesis for dansyl homocysteine is described and this fluorescent thiol is used as a direct and sensitive nitric oxide-transfer probe. The results demonstrate that redox turnover of copper is required for efficient nitric oxide transfer between low-molecular-weight thiols.