The thermal stability of a castor bean seed acid phosphatase.
The effect of temperature on the activity and structural stability of an acid phosphatase (EC 3.1.3.2.) purified from castor bean (Ricinus communis L.) seeds have been examined. The enzyme showed high activity at 45 degrees C using p-nitrophenylphosphate (p-NPP) as substrate. The activation energy for the catalyzed reaction was 55.2 kJ mol(-1) and the enzyme maintained 50% of its activity even after 30 min at 55 degrees C. Thermal inactivation studies showed an influence of pH in the loss of enzymatic activity at 60 degrees C. A noticeable protective effect from thermal inactivation was observed when the enzyme was preincubated, at 60 degrees C, with the reaction products inorganic phosphate-P (10 mM) and p-nitrophenol-p-NP(10 mM). Denaturation studies showed a relatively high transition temperature (Tm) value of 75 degrees C and an influence of the combination of Pi (10 mM) and p-NP (10 mM) was observed on the conformational behaviour of the macromolecule.
Granjeiro
Paulo Afonso
PA
Departamento de Bioquímica, Instituto de Biologia, Universidade Estadual de Campinas, São Paulo, Brazil.
Cavagis
Alexandre Donizeti Martins
AD
de Campos Leite
Luciana
L
Ferreira
Carmen Veríssima
CV
Granjeiro
José Mauro
JM
Aoyama
Hiroshi
H
D000135:Acid Phosphatase / Q000737:chemistry*; D002367:Ricinus communis / Q000201:enzymology*; D004795:Enzyme Stability; D006358:Hot Temperature; D009596:Nitrophenols / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry*; D011489:Protein Denaturation; D012639:Seeds / Q000201:enzymology*; D013816:Thermodynamics
D009596:Nitrophenols; D009943:Organophosphorus Compounds; D010710:Phosphates; D010940:Plant Proteins; C008644:nitrophenylphosphate; D000135:Acid Phosphatase