Purification and characterization of glutamate decarboxylase from cowpea
1997; Elsevier BV; Volume: 46; Issue: 1 Linguagem: Inglês
10.1016/s0031-9422(97)00236-7
ISSN1873-3700
AutoresBrandon S. Johnson, Narendra K. Singh, Joe H. Cherry, Robert D. Locy,
Tópico(s)Biochemical Analysis and Sensing Techniques
ResumoGlutamate decarboxylase (GAD) was purified 300-fold from green cowpea (Vigna unguiculata L.) pods using a combination of PEG precipitation, DEAE cellulose chromatography, hydroxylapatite chromatography, and Q-resin chromatography. The partially purified preparation demonstrated 2 primary bands in SDS-polyacrylamide gel electrophoresis with up to 3 additional minor bands. Cowpea GAD has a pH optimum at between pH 5.5–6.0, and an apparent KM for glutamate of 3.2 mM at pH 5.8. Both crude GAD preparations and preparations partially purified through the hydroxylapatite step can be stimulated by Ca2+ and calmodulin when assayed at pH 5.8. However, the purified enzyme does not show activation by Ca2+ and/or calmodulin at pH 5.8 or at pH 7.0. © 1997 Elsevier Science Ltd. All rights reserved
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