Electrochemical assay for determining nitrosyl derivatives of human hemoglobin: nitrosylhemoglobin and S-nitrosylhemoglobin

Abstract

Nitric oxide (NO) is an important biological regulator. It can bind to heme iron and form NO +, involved in the synthesis of S-nitrosothiols (–SNOs). NO reacts with human hemoglobin (Hb) to produce the derivatives: S-nitrosylhemoglobin (–SNOHb) and nitrosylhemoglobin (HbNO). At neutral pH values, free NO does not react directly with the –SH groups of Hb. The reductive nitrosylation of Fe(III) heme upon reaction with NO has long been studied, but it is not yet completely known. To quantify the reaction of NO with Hb, we developed a new, sensitive (nanomolar concentration range) electrochemical assay to selectively measure HbNO and –SNOHb. The assay also allows the monitoring of free NO during the reaction with human Fe(III)Hb and Fe(II)HbO 2.