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Characterization of the isozymes of glucuronoxylan xylanohydrolase in the presence of a native cell wall substrate
Author(s) -
Hayashi K.,
Inouhe M.,
Aoyagi C.,
Nevins D.J.
Publication year - 1996
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/j.1472-765x.1996.tb01164.x
Subject(s) - isozyme , coleoptile , amino acid , chemistry , residue (chemistry) , ion chromatography , biochemistry , molecular mass , enzyme , chromatography , substrate (aquarium) , cell wall , biology , ecology
K. HAYASHI, M. INOUHE, C. AOYAGI AND D.J. NEVINS. 1996. A simple but accurate method for measuring glucuronoxylan xylanohydrolase activity was developed using coleoptile cell wall particles prepared from maize ( Zea mays L.). Two isozymes of glucuronoxylan xylanohydrolases designated as GX1 and GX2 (EC 3.2.1.136) were purified from a commercially available amylase preparation to electrophoretic homogeneity by three cation exchange chromatography steps. Upon characterization no significant differences between the two enzymes were detected: the molecular mass measured by MALDITOF mass spectrometry was 44 360 100 for GX1 and 44 370 50 for GX2 suggesting no difference in the total number of amino acid residues. Furthermore the N ‐terminal amino acid sequence for each of the isozymes was identical through the 37th amino acid residue. The values of pI were determined to be 9.0 for GX1 and 9.1 for GX2. The sensitivity to temperature, pH and to ionic strength was similar for both isozymes as were kinetic parameters including K m and V max m No differences could be detected in substrate specificity.