title: Soybean seed acid phosphatases: unusual optimum temperature and thermal stability studies.
abstract: In contrast to other acid phosphatases, four cytoplasmic isoforms (AP1, AP2, AP3A, and AP3B) purified from mature soybean seeds presented high activities at temperatures above 80 degrees C, when p-nitrophenylphosphate (p-NPP) was utilized as substrate. However, with tyrosine phosphate and inorganic pyrophosphate as substrates, maximum activities were observed at temperature of 60 degrees C during 10 min reaction. In the absence of substrate, enzymes lost only 20% activity after 60 min at 60 degrees C; the isoforms AP3A and AP3B retained 30% of activity at 70 degrees C after 60 min and all the isoforms were inactivated at 80 degrees C, after 5 min. Thermal inactivation studies indicated that the soybean enzymes showed different temperature dependences in relation to most plant acid phosphatases. A best protective effect was observed when the isoforms were preincubated, at 70 degrees C, with phosphate (10 mM) and p-nitrophenol (10 mM) which indicates that the enzyme inactivation was prevented only in the presence of both reaction products.
authors.affiliation: Departmento de Bioquimica, Universidade Estadual de Campinas, São Paulo, Brazil.
authors.forename: C V
authors.initials: CV
authors.lastname: Ferreira
authors.forename: J M
authors.initials: JM
authors.lastname: Granjeiro
authors.forename: E M
authors.initials: EM
authors.lastname: Taga
authors.forename: H
authors.initials: H
authors.lastname: Aoyama
mesh_terms: D000135:Acid Phosphatase / Q000302:isolation & purification / Q000378:metabolism*; D003593:Cytoplasm / Q000201:enzymology; D011756:Diphosphates / Q000378:metabolism; D004795:Enzyme Stability; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D009596:Nitrophenols / Q000378:metabolism / Q000494:pharmacology; D017830:Octoxynol / Q000494:pharmacology; D009943:Organophosphorus Compounds / Q000378:metabolism; D010710:Phosphates / Q000494:pharmacology; D019000:Phosphotyrosine / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D012639:Seeds / Q000201:enzymology; D013025:Glycine max / Q000201:enzymology*; D013696:Temperature; D014638:Vanadates / Q000494:pharmacology
chemical_list: D011756:Diphosphates; D007527:Isoenzymes; D009596:Nitrophenols; D009943:Organophosphorus Compounds; D010710:Phosphates; D010940:Plant Proteins; D019000:Phosphotyrosine; C008644:nitrophenylphosphate; D014638:Vanadates; D017830:Octoxynol; D000135:Acid Phosphatase; C024836:4-nitrophenol