title: Application of 13C-NMR spectroscopy to in vitro analysis of enzyme kinetics.
abstract: The conversion of D,L-alpha-13C-histidine to similarly labeled alpha-13C histamine by bacterial and mammalian histidine decarboxylase was studied by 13C-NMR spectroscopy and GLC-mass spectrometry. The results obtained with the partially purified bacterial enzyme were in essentially perfect agreement with results obtained simultaneously with a standard  radioisotopic  method using carboxyl-labeled-14C-L-histidine. For a crude tissue preparation of the mammalian enzyme, the radioisotopic method indicated an activity three times that based on 13C-NMR measurement of alpha-13C-histamine. The difference in results was accountable in terms of additional 13C-NMR signals attributable to  products other than histamine due in part to enzymatic degradation of the latter.
mesh_terms: D000818:Animals; D002247:Carbon Isotopes; D002250:Carbon Radioisotopes; D002262:Carboxy-Lyases / Q000378:metabolism*; D003016:Clostridium perfringens / Q000201:enzymology; D006640:Histidine Decarboxylase / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D013058:Mass Spectrometry; D051381:Rats; D013270:Stomach / Q000201:enzymology
chemical_list: D002247:Carbon Isotopes; D002250:Carbon Radioisotopes; D002262:Carboxy-Lyases; D006640:Histidine Decarboxylase