Inhibition of the catalytic activity of human transaldolase by antibodies and site-directed mutagenesis.
Transaldolase is a key enzyme of the pentose phosphate pathway. While antibody (Ab) 169, directed against the N-terminal 139 residues of human transaldolase (TAL-H), had no effect on enzyme activity, Ab 12484 raised against full length and functional recombinant TAL-H inhibited catalytic activity. This tentatively mapped the catalytic site to the C-terminal 140-336 amino acid portion of TAL-H. Dihydroxyacetone transfer reactions catalyzed by transaldolase depend on Schiff base formation by a lysine residue. Replacement of lysine-142 by glutamine using site-directed mutagenesis resulted in a complete loss of enzyme activity, suggesting that lysine-142 is essential for the catalytic activity of TAL-H.
Department of Pathology, State University of New York, College of Medicine, Syracuse 13210, USA.
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D000595:Amino Acid Sequence; D000906:Antibodies / Q000494:pharmacology*; D001483:Base Sequence; D001665:Binding Sites; D002384:Catalysis; D006801:Humans; D008239:Lysine; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000037:antagonists & inhibitors; D011994:Recombinant Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship; D014153:Transaldolase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics
D000906:Antibodies; D010446:Peptide Fragments; D011994:Recombinant Proteins; D014153:Transaldolase; D008239:Lysine