Document Detail


Isolation and partial characterisation of acid phosphatase isozymes from dormant oilseed of Corylus avellana L.
MedLine Citation:
PMID:  15048567     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The acid phosphatase (orthophosphoric-monoester phosphohydrolase, EC 3.1.3.2) complement from dormant hazel (Corylus avellana L.) seeds was found to exhibit significant electrophoretic heterogeneity partially attributable to the presence of distinct molecular forms. In axiferous tissue, total acid phosphatase activity increased in a biphasic fashion during chilling, a treatment necessary to alleviate seed dormancy. Three acid phosphatase isozymes were isolated from cotyledons of dormant hazel seeds by successive ammonium sulphate precipitation, size-exclusion, Concanavalin A affinity, cation- and anion-exchange chromatographies resulting in 75-, 389- and 191-fold purification (APase1, APase2, APase3, respectively). The three glycosylated isoforms were isolated to catalytic homogeneity as determined by electrophoretic, kinetic and heat-inactivation studies. The native acid phosphatase complement of hazel seeds had an apparent Mr of 81.5 +/- 3.5 kDa as estimated by size-exclusion chromatography, while the determined pI values were 5.1 (APase1), 6.9 (APase2) and 7.3 (APase3). The optimum pH for p-nitrophenyl phosphate hydrolysis was pH 3 (APase1), pH 5.6 (APase2) and pH 6 (APase3). The hazel isozymes hydrolysed a variety of phosphorylated substrates in a non-specific manner, exhibiting low Km and the highest specificity constant (Vmax/ Km) for pyrophosphate. They were not primary phytases since they could not initiate phytic acid hydrolysis, while APase2 and APase3 had significant phospho-tyrosine phosphatase activity. Inorganic phosphate was a competitive inhibitor, while activity was significantly impaired in the presence of vanadate and fluoride.
Authors:
Vasilios M E Andriotis; James D Ross
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2004-03-27
Journal Detail:
Title:  Planta     Volume:  219     ISSN:  0032-0935     ISO Abbreviation:  Planta     Publication Date:  2004 Jun 
Date Detail:
Created Date:  2004-06-01     Completed Date:  2004-08-31     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  1250576     Medline TA:  Planta     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  346-58     Citation Subset:  IM    
Copyright Information:
Copyright 2004 Springer-Verlag
Affiliation:
School of Plant Sciences, The University of Reading, Whiteknights, Reading, RG6 6AS, UK.
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MeSH Terms
Descriptor/Qualifier:
Acid Phosphatase / chemistry*,  metabolism
Chromatography, Affinity
Corylus / enzymology*
Germination
Hydrogen-Ion Concentration
Isoenzymes / metabolism
Kinetics
Molecular Weight
Plant Proteins / metabolism
Seeds / enzymology,  growth & development
Substrate Specificity
Chemical
Reg. No./Substance:
0/Isoenzymes; 0/Plant Proteins; EC 3.1.3.2/Acid Phosphatase

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