TY - JOUR
T1 - Mechanism of inactivation of γ-aminobutyric acid aminotransferase by (S)-4-amino-4,5-dihydro-2-thiophenecarboxylic acid
AU - Fu, Mengmeng
AU - Nikolic, Dejan
AU - Van Breemen, Richard B.
AU - Silverman, Richard B.
PY - 1999/9/1
Y1 - 1999/9/1
N2 - (S)-4-Amino-4,5-dihydro-2-thiophenecarboxylic acid ((S)-6) was previously synthesized (Adams, J. L.; Chen, T. M.; Metcalf, B. W. J. Org. Chem. 1985, 50, 2730-2736.) as a heterocyclic mimic of the natural product gabaculine (5-amino-1,3-cyclohexadienylcarboxylic acid), a mechanism-based inactivator of γ-aminobutyric acid aminotransferase (GABA-AT) (Rando, R. R. Biochemistry 1977, 16, 4604). Inactivation of GABA-AT by (S)-6 is time- dependent and protected by substrate. Two methods were utilized to demonstrate that, in addition to inactivation, about 0.7 equiv per inactivation event undergoes transamination. Inactivation results from the reaction of (S)-6 with the pyridoxal 5'-phosphate (PLP) cofactor. The adduct was isolated and characterized by ultraviolet-visible spectroscopy, electrospray mass spectrometry, and tandem mass spectrometry. All of the results support a structure (11) that derives from the predicted aromatization inactivation mechanism (Scheme 2) originally proposed by Metcalf and co-workers for this compound. This is only the third example, besides gabaculine and L-cycloserine, of an inactivator of a PLP-dependent enzyme that acts via an aromatization mechanism.
AB - (S)-4-Amino-4,5-dihydro-2-thiophenecarboxylic acid ((S)-6) was previously synthesized (Adams, J. L.; Chen, T. M.; Metcalf, B. W. J. Org. Chem. 1985, 50, 2730-2736.) as a heterocyclic mimic of the natural product gabaculine (5-amino-1,3-cyclohexadienylcarboxylic acid), a mechanism-based inactivator of γ-aminobutyric acid aminotransferase (GABA-AT) (Rando, R. R. Biochemistry 1977, 16, 4604). Inactivation of GABA-AT by (S)-6 is time- dependent and protected by substrate. Two methods were utilized to demonstrate that, in addition to inactivation, about 0.7 equiv per inactivation event undergoes transamination. Inactivation results from the reaction of (S)-6 with the pyridoxal 5'-phosphate (PLP) cofactor. The adduct was isolated and characterized by ultraviolet-visible spectroscopy, electrospray mass spectrometry, and tandem mass spectrometry. All of the results support a structure (11) that derives from the predicted aromatization inactivation mechanism (Scheme 2) originally proposed by Metcalf and co-workers for this compound. This is only the third example, besides gabaculine and L-cycloserine, of an inactivator of a PLP-dependent enzyme that acts via an aromatization mechanism.
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U2 - 10.1021/ja9915551
DO - 10.1021/ja9915551
M3 - Article
AN - SCOPUS:0033198649
VL - 121
SP - 7751
EP - 7759
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 34
ER -