A method for the isolation and identification of pyridoxal phosphate in proteins

Buffoni, F.; Cambi, S.

doi:10.1016/0003-2697(90)90414-5

Cited by 14 publications

(2 citation statements)

References 12 publications

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“…Nevertheless, it was recently claimed that pyridoxal phosphate can be extracted from plasma amine oxidase [177] and several indirect arguments have been put forward in Favor of this cofactor in the case of lysyl oxidase 11781. In view of the strong evidence for TPQ, the finding of pyridoxal phosphate should be confirmed before taking its presence for granted.…”

Section: Structure and Mechanismmentioning

confidence: 99%

Quinoproteins: enzymes containing the quinonoid cofactor pyrroloquinoline quinone, topaquinone or tryptophan‐tryptophan quinone

Duine¹

1991

European Journal of Biochemistry

198

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The presently best known and largest group of quinoproteins consists of enzymes using the cofactor 2,7,9-tricarboxy-1 H-pyrrolo[2,3-S]quinoline-4,5-dione (PQQ), a compound having a pyrrole ring fused to a quinoline ring with an o-quinone group in it. Representatives of this group are found among the bacterial, NAD(P)-independent, periplasmic dehydrogenases. Despite their high midpoint redox potential, the overall behaviour of quinoprotein dehydrogenases is similar to that of their counterparts, those using a flavin cofactor or a nicotinamide coenzyme. Apart from an exceptional Gram-positive one, the sole organisms where the presence of PQQ has really been established are Gram-negative bacteria. Evidence for the occurrence of covalently bound PQQ is lacking since it has now been shown that several enzymes previously considered to contain this prosthetic group do not in fact do so.Another group of quinoproteins, consisting of amine oxidoreductases, has a protein chain containing one of the following quinonoid aromatic amino acids: 6-hydroxy-phenylalanine-3,4-dione (TPQ) or 4-(2'-tryptophy1)-tryptophan-6,7-dione (TTQ). There is no doubt that these o-quinones play a role as cofactor, in the case of TPQ in prokaryotic as well as eukaryotic amine oxidases. It appears, therefore, that a novel class of amino-acid-derived cofactors is emerging, ranging from the free radical form of tyrosine and tryptophan to those containing a dicarbonyl group (like the already known pyryvoyl group and the o-quinones here described). THE QUINONOID COFACTORS IdentificationAbout ten years ago, the structure of the cofactor of methanol dehydrogenase (EC 1.1.99.8) was elucidated [l, 21. The compound (Fig. 1) has been given the names of pyrroloquinoline quinone (PQQ) and methoxatin. Since it appeared that many other dehydrogenases from Gram-negaCorrespondence to J. A. Duine, Department of Microbiology and Enzymology, Delft University of Technology, Julianalaan 67, NL-2628 BC Delft, The NetherlandsAbbreviations. PQQ, pyrroloquinoline quinone, 2,7,9-tricarboxy-1 H-pyrr010[2,3~/]quinoline-4,5-dione; PQQH', PQQH,, PQQH,, the one-, two-, and four-electron reduced forms of PQQ; PQQ-H20, PQQ with covalently bound H 2 0 at the C5 position; PQ, pyrroloquinoline, 2,7,9-tricarboxy-1H-pyrrolo[2,3-flquinoline; TPQ, topaquinone, 6-hydroxy-phenylalanine-3,4-dione; TTQ, tryptophan-tryptophan quinone, 4-(2'-tryptophyl)-tryptophan-6,7-dione.Enzvmes. tive bacteria contain this cofactor, in analogy with the usual terminology in enzymology (e.g. flavoproteins, haemoproteins) the name quinoproteins was introduced for these enzymes [2]. During the past decade, much has already been revealed of this novel branch of enzymology, as demonstrated in a number of reviews on PQQ [3, 41 and quinoproteins [5, 61, and in the proceedings of the first international symposium on this topic [7].About five years ago, the presence of covalently bound PQQ in copper-containing plasma amine oxidase (EC 1.4.3.6) was reported, as was concluded from the detection of PQQ after acid hyd...

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Section: Structure and Mechanismmentioning

confidence: 99%

Quinoproteins: enzymes containing the quinonoid cofactor pyrroloquinoline quinone, topaquinone or tryptophan‐tryptophan quinone

Duine¹

1991

European Journal of Biochemistry

198

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“…Although BSAO has been studied extensively since the 1950s, identification of the carbonyl cofactor has been hindered by its inherent reactivity and the fact that it is covalently linked to enzyme. The inability to isolate and characterize the cofactor has resulted in conflicting hypotheses regarding cofactor structure, which was originally attributed to pyridoxal phosphate (Buffoni, 1966;Buffoni & Cambi, 1990) and, later, to pyrroloquinoline quinone (Lobenstein-Verbeek et al, 1984;Ameyama et al, 1984). Recently, this ambiguity has been resolved with the identification of 6-hydroxydopa (topa) at the active site of BSAO (Janes et al, 1990).…”

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confidence: 99%

An investigation of bovine serum amine oxidase active site stoichiometry: evidence for an aminotransferase mechanism involving two carbonyl cofactors per enzyme dimer

Janes

Klinman²

1991

Biochemistry

123

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Recent evidence has shown that the active site cofactor in bovine serum amine oxidase (BSAO) is 2,4,5-trihydroxyphenylalanine or 6-hydroxydopa [Janes et al. (1990) Science 248, 981]. However, much ambiguity remains regarding the mechanism of the enzymatic reaction. Conflicting data exist for both the number of functional active sites in the dimeric enzyme and for the oxygen dependence of product release. To resolve these questions, a new method has been developed for the purification of BSAO which leads to the isolation of specific activity greater than or equal to 0.4 unit/mg of enzyme in 2-3 weeks. This highly active enzyme has been used to quantitate both aldehyde and ammonia release in the reductive half-reaction. Anaerobic incubation of enzyme and substrate resulted in the production of 2 mol of aldehyde/mol of enzyme, indicating the presence of a cofactor at each enzyme subunit. As anticipated for an aminotransferase reaction, no ammonia release was detected under comparable conditions. Active site titration of enzyme samples of varying specific activity with phenylhydrazine extrapolates to 1 mol of inhibitor/mol of enzyme subunit for BSAO of specific activity = 0.48 unit/mg. These findings contrast with numerous, previous reports of only one functional cofactor per enzyme dimer in copper amine oxidases.

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Quinoproteins: enzymes containing the quinonoid cofactor pyrroloquinoline quinone, topaquinone or tryptophan-tryptophan quinone

Duine¹

1991

EJB Reviews 1991

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A method for the isolation and identification of pyridoxal phosphate in proteins

Cited by 14 publications

References 12 publications

Quinoproteins: enzymes containing the quinonoid cofactor pyrroloquinoline quinone, topaquinone or tryptophan‐tryptophan quinone

Quinoproteins: enzymes containing the quinonoid cofactor pyrroloquinoline quinone, topaquinone or tryptophan‐tryptophan quinone

An investigation of bovine serum amine oxidase active site stoichiometry: evidence for an aminotransferase mechanism involving two carbonyl cofactors per enzyme dimer

Quinoproteins: enzymes containing the quinonoid cofactor pyrroloquinoline quinone, topaquinone or tryptophan-tryptophan quinone

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