Separation and characterization of a salt-dependent pectin methylesterase from Citrus sinensis var. Valencia fruit tissue.
J Agric Food Chem
; 51(7): 2070-5, 2003 Mar 26.
Article
en En
| MEDLINE
| ID: mdl-12643675
ABSTRACT
A pectin methylesterase (PME) from sweet orange fruit rag tissue, which does not destabilize citrus juice cloud, has been characterized. It is a salt-dependent PME (type II) and exhibits optimal activity between 0.1 and 0.2 M NaCl at pH 7.5. The pH optimum shifted to a more alkaline range as the salt molarity decreased (pH 8.5-9.5 at 50 mM NaCl). It has an apparent molecular mass of 32.4 kDa as determined by gel filtration chromatography, an apparent molecular mass of 33.5 kDa as determined by denaturing electrophoresis, and a pI of 10.1 and exhibits a single activity band after isoelectric focusing (IEF). It has a K(m) of 0.0487 mg/mL and a V(max) of 4.2378 nkat/mg of protein on 59% DE citrus pectin. Deblocking the N-terminus revealed a partial peptide composed of SVTPNV. De-esterification of non-calcium-sensitive pectin by 6.5% increased the calcium-sensitive pectin ratio (CSPR) from 0.045 +/- 0.011 to 0.829 +/- 0.033 but had little, if any, effect on pectin molecular weight. These properties indicate this enzyme will be useful for studying the PME mode of action as it relates to juice cloud destabilization.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Hidrolasas de Éster Carboxílico
/
Cloruro de Sodio
/
Citrus sinensis
/
Frutas
Idioma:
En
Revista:
J Agric Food Chem
Año:
2003
Tipo del documento:
Article
País de afiliación:
Estados Unidos