Purification of class 1 plant hemoglobins and examination of their functional properties.

Class 1 hemoglobins are ubiquitous plant proteins induced under hypoxic conditions. They bind oxygen tightly and, as oxyhemoglobin, react with nitric oxide produced under hypoxic conditions. The reactions involved in NO production and scavenging help maintain the redox and energy status of the cell. This article describes the expression of class 1 barley (Hordeum vulgare L.) hemoglobin in E. coli cells and its purification to homogeneity. Methods for investigating the properties of purified hemoglobin and for measuring its nitric oxide scavenging activity are described. A method for isolation of a plant methemoglobin reductase is also presented.