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On the biosynthesis of free and covalently bound PQQ Glutamic acid decarboxylase from Escherichia coli is a pyridoxo‐quinoprotein
Author(s) -
van der Meer Robert A.,
Groen Barend W.,
Duine Johannis A.
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)80263-7
Subject(s) - escherichia coli , chemistry , biochemistry , biosynthesis , covalent bond , glutamate decarboxylase , glutamic acid , enzyme , amino acid , organic chemistry , gene
Analysis of glutamic acid decarboxylase (GDC) (EC 4.1.1.15) from Escherichia coli ATCC 11246 revealed the presence of six pyridoxal phosphates (PLPs) as well as six covalently bound pyrroloquinoline quinones (PQQs) per hexameric enzyme molecule. This is the second example of a pyridoxo‐quinoprotein, suggesting that other atypical pyridoxoproteins (PLP‐containing enzymes) have similar cofactor composition. Since the organism did not produce free PQQ and its quinoprotein glucose dehydrogenase was present in the apo form, free PQQ is not used in the assemblage of GDC. Most probably, biosynthesis of covalently bound cofactor occurs in situ via a route which is different from that of free PQQ. Thus, organisms previously believed to be unable to synthesize (free) PQQ could in fact be able to produce quinoproteins with covalently bound cofactor. Implications for the role of PQQ in eukaryotic cells are discussed.