Local changes in the catalytic site of mammalian histidine decarboxylase can affect its global conformation and stability.
Mature, active mammalian histidine decarboxylase is a dimeric enzyme of carboxy-truncated monomers (approximately 53 kDa). By using a biocomputational approach, we have generated a three-dimensional model of a recombinant 1/512 fragment of the rat enzyme, which shows kinetic constants similar to those of the mature enzyme purified from rodent tissues. This model, together with previous spectroscopic data, allowed us to postulate that the occupation of the catalytic center by the natural substrate, or by substrate-analogs, would induce remarkable changes in the conformation of the intact holoenzyme. To investigate the proposed conformational changes during catalysis, we have carried out electrophoretic, chromatographic and spectroscopic analyses of purified recombinant rat 1/512 histidine decarboxylase in the presence of the natural substrate or substrate-analogs. Our results suggest that local changes in the catalytic site indeed affect the global conformation and stability of the dimeric protein. These results provide insights for new alternatives to inhibit histamine production efficiently in vivo.
Rodríguez-Caso
Carlos
C
Department of Molecular Biology and Biochemistry, Faculty of Sciences, Málaga, Spain.
Rodríguez-Agudo
Daniel
D
Moya-García
Aurelio A
AA
Fajardo
Ignacio
I
Medina
Miguel Angel
MA
Subramaniam
Vinod
V
Sánchez-Jiménez
Francisca
F
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D020134:Catalytic Domain; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D006640:Histidine Decarboxylase / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D011994:Recombinant Proteins; D006640:Histidine Decarboxylase