Purification and characterization of cytosolic glyceraldehyde-3-phosphate dehydrogenase from the dromedary camel.
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (EC 1.2.1.12), a key enzyme of carbon metabolism, was purified and characterized to homogeneity from skeletal muscle of Camelus dromedarius. The protein was purified approximately 26.8 folds by conventional ammonium sulphate fractionation followed by Blue Sepharose CL-6B chromatography, and its physical and kinetic properties were investigated. The native protein is a homotetramer with an apparent molecular weight of approximately 146 kDa. Isoelectric focusing analysis showed the presence of only one GAPDH isoform with an isoelectric point of 7.2. The optimum pH of the purified enzyme was 7.8. Studies on the effect of temperature on enzyme activity revealed an optimal value of approximately 28-32 degrees with activation energy of 4.9 kcal/mol. The apparent K(m) values for NAD(+) and DL-glyceraldehyde-3-phophate were estimated to be 0.025+/-0.040 mM and 0.21+/-0.08 mM, respectively. The V(max) of the purified protein was estimated to be 52.7+/-5.9 U/mg. These kinetic parameter values were different from those described previously, reflecting protein differences between species.
Fourrat
Latifa
L
Laboratoire de Physiologie et Genetique Moleculaire, Departement de Biologie, Faculte des Sciences Ain-Chock, Universite Hassan-II., Casablanca, Morocco.
Iddar
Abdelghani
A
Soukri
Abdelaziz
A
D000818:Animals; D002162:Camelus; D002852:Chromatography, Ion Exchange; D003600:Cytosol / Q000201:enzymology*; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000302:isolation & purification* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D018482:Muscle, Skeletal / Q000201:enzymology*; D013816:Thermodynamics
D005987:Glyceraldehyde-3-Phosphate Dehydrogenases