Characterization of porcine Alpha-class glutathione transferase A1-1

• An Alpha-class glutathione transferase (GST) has been cloned from pig gonads. In addition to two conservative point mutations our nucleotide sequence presents a frame shift resulting from a missing A as compared to a previously published porcine GST A1-1 sequence. The deduced C-terminal amino-acid segment of the protein differs between the two variants. Repeated sequencing of cDNA isolated from different tissuesand animals ruled out the possibility of a cloning artifact, and the deduced amino acid sequence ofour clone showed higher similarity to related mammalian GST sequences. Hereafter, we refer to ourcloned enzyme as GST A1-1 and to the previously published enzyme as GST A1-1*. The study of the tissue distribution of the GSTA1 mRNA revealed high expression levels in many organs, in particular adipose tissue, liver, and pituitary gland. Porcine GST A1-1 was expressed in Escherichia coli and its kinetic properties were determined using alternative substrates. The catalytic activity in steroid isomerization reactionswas at least 10-fold lower than the corresponding values for porcine GST A2-2, whereas the activity with 1-chloro-2,4-dinitrobenzene was approximately 8-fold higher. Differences in the H-site residues of mammalian Alpha-class GSTs may explain the catalytic divergence.

Ämnesord

NATURVETENSKAP  -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

Sus scrofa

glutathione transferase A1-1

alternative sequence

substrate selectivity

Biochemistry

Biokemi

Biokemi

Biochemistry

Neurochemistry and Molecular Neurobiology

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