Acid glutathione S-transferase from human liver: preliminary report

Abstract

An acid glutathione S-transferase from human liver has been partially purified and characterized. The relative molecular mass of the enzyme is 46,000, and a double reciprocal plot of velocity against glutathione concentration is biphasic and shows in addition substrate inhibition. The enzyme differs from the basic human liver transferases α, β, γ, δ and e in the characteristics studied, but it bears a resemblance to transferase p from human erythrocytes. When liver cytosol was analysed by isoelectric focusing using a short pH gradient and a density gradient formed of either glycerol or saccharose, the peak of glutathione S-transferase activity appeared at pH 4.63 ± 0.02, in contrast to blood cell lysate which was found to contain a major peak at pH 4.63 and at least two additional peaks at pH 4.44 and 4.51, respectively.

Key Words:

• glutathione
• ligandin (glutathione S-transferase B)
• substrate concentration dependent kinetics