Kinetics of manganese reconstitution and thiol group exposition in dialyzed rat mammary gland arginase.
1. Rat mammary gland arginase is a metallo-enzyme dependent on Mn2+, which can be only partially substituted by Cd2+. 2. Reconstitution of the activity of dialyzed arginase by manganese is a two-phase process; the second phase is independent of the cation concentration, with a half-time recovery (t1/2) of 10.77 min. 3. The apparent Km for Mn2+ is 280 microM and 10.5 microM for enzyme dialyzed for 24 and 72 hr, respectively. 4. Treatment with 5 mM EDTA at pH 6 totally inhibits enzyme activity, which is reconstituted by Mn2+. 5. Results obtained with iodoacetamide treatment suggest the existence of sulphydryl groups accessible only when the enzyme is dialyzed.
Fuentes
J M
JM
Departamento de Bioquímica, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain.
Campo
M L
ML
Soler
G
G
D000818:Animals; D001119:Arginase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003956:Dialysis; D004492:Edetic Acid / Q000494:pharmacology; D005260:Female; D006863:Hydrogen-Ion Concentration; D007460:Iodoacetamide / Q000494:pharmacology; D007774:Lactation; D008321:Mammary Glands, Animal / Q000201:enzymology*; D008345:Manganese / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D013439:Sulfhydryl Reagents / Q000494:pharmacology
D013438:Sulfhydryl Compounds; D013439:Sulfhydryl Reagents; D008345:Manganese; D004492:Edetic Acid; D001119:Arginase; D007460:Iodoacetamide