Purification and characterization of developmentally regulated AMP deaminase from Dictyostelium discoideum.
AMP deaminase, the enzyme that catalyzes the conversion of adenosine monophosphate (AMP) to inosine monophosphate (IMP) and ammonia, was purified from the cellular slime mold, Dictyostelium discoideum in the nutrient-deprived state. The native enzyme had an apparent molecular weight of 199,000 daltons. Its apparent Km was 1.6 mM and its Vmax was 1.0 mumol min-1 mg-1, as measured by the release of IMP From AMP. The enzyme, like other AMP deaminases, was found to be activated by ATP, and inhibited either by GTP or inorganic phosphate. It was also specific for the deamination of AMP. Deaminase activity was increased either when vegetative cells were placed in a nutrient-deprived medium (for up to 6 h) or when vegetative cells were treated with the drug hadacidin. In cells actively growing in complete media, enzyme activity was more non-specific, hydrolyzing adenosine as well as AMP. AMP deaminase in D. discoideum appears to be stage-specific and developmentally regulated, possibly serving to regulate the adenylated nucleotide pool and the interconversion to guanylated nucleotides during early morphodifferentiation.
Department of Chemistry, University of Lowell, MA 01854.
D P
DP
Malliaros
D L
DL
Kozwich
E G
EG
Jahngen
D000659:AMP Deaminase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D002845:Chromatography; D003520:Cyclophosphamide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004023:Dictyostelium / Q000201:enzymology* / Q000254:growth & development; D004305:Dose-Response Relationship, Drug; D005612:Freeze Drying; D015971:Gene Expression Regulation, Enzymologic; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology; D008970:Molecular Weight; D010710:Phosphates / Q000494:pharmacology; D013010:Sonication; D013379:Substrate Specificity
D000903:Antibiotics, Antineoplastic; D010710:Phosphates; D003609:Dactinomycin; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D003520:Cyclophosphamide; C001321:hadacidin; D000659:AMP Deaminase; D005998:Glycine