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Iron—sulfur cluster‐containing l ‐serine dehydratase from Peptostreptococcus asaccharolyticus : Correlation of the cluster type with enzymatic activity
Author(s) -
Hofmeister A.E.M.,
Albracht S.P.J.,
Buckel W.
Publication year - 1994
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(94)00901-5
Subject(s) - dehydratase , chemistry , enzyme , aconitase , serine , biochemistry , iron–sulfur cluster , pyridoxal phosphate , stereochemistry , cofactor
Investigations were performed with regard to the function of the iron—sulfur cluster of l ‐serine dehydratase from Peptostreptococcus asaccharolyticus , an enzyme which is novel in the class of deaminating hydro‐lyases in that it lacks pyridoxal‐5′‐phosphate. Anaerobically purified l ‐serine dehydratase from P. asaccharolyticus revealed EPR spectra characteristic of a [3Fe–4S] + cluster constituting 1% of the total enzyme concentration. Upon incubation of the enzyme under air the intensity of the [3Fe–4S] + signal increased correlating with the loss of enzymatic activity. Addition of l ‐serine prevented this. Hence, active l ‐serine dehydratase probably contains a diamagnetic [4Fe–4S] 2+ cluster which is converted by oxidation and loss of one iron ion to a paramagnetic [3Fe–4S] + cluster, resulting in inactivation of the enzyme. In analogy to the mechanism elucidated for aconitase, it is proposed that l ‐serine is coordinated via its hydroxyl and carboxyl groups to the labile iron atom of the [4Fe–4S] 2+ cluster.