Evidence for PQQ as cofactor in 3,4‐dihydroxyphenylalanine (dopa) decarboxylase of pig kidney

FEBS Letters

Groen, Barend W.¹  Duine, Joannis A.¹  van der Meer, Robert A.¹ 

[1] Department of Microbiology and Enzymology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands

关键词: 3;    4-Dihydroxyphenylalanine decarboxylase;    Pyrroloquinoline quinone;    Pyridoxal phosphate;    Cofactor;    Quinoprotein;    Hydrazone;    (Pig kidney);   

DOI  :  10.1016/0014-5793(88)80179-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Pig kidney 3,4-dihydroxyphenylalanine (dopa) decarboxylase (EC 4.1.1.28) was purified to homogeneity. Treatment of the enzyme with phenylhydrazine (PH) according to a procedure developed for analysis of quinoproteins gave products which were identified as the hydrazone of pyridoxal phosphate (PLP) and the C(5)-hydrazone of pyrroloquinoline quinone (PQQ). This method failed, however, in quantifying the amounts of cofactor. Direct hydrolysis of the enzyme by refluxing with hexanol and concentrated HCl led to detachment of PQQ from the protein in a quantity of 1 PQQ per enzyme molecule. In view of the reactivity of PQQ towards amines and amino acids, we postulate that it participates as a covalently bound cofactor in the catalytic cycle of the enzyme, in interplay with PLP. Since several other enzymes have been reported to show the atypical behaviour of dopa decarboxylase, it seems that the PLP-containing group of enzymes can be subdivided into pyridoxoproteins and pyridoxo-quinoproteins.

【 授权许可】

Unknown