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Acetohydroxyacid synthase from Claviceps purpurea : Partial purification and characterization
Author(s) -
Maier Walter,
Luthra Rajesh,
Gröger Detlef
Publication year - 1989
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.3620290802
Subject(s) - chemistry , enzyme , biochemistry , chromatography , ammonium sulfate , thiamine pyrophosphate , sepharose , cofactor
An acetohydroxyacid synthase (EC 4.1.3.18) which synthesizes α‐acetolactate from pyruvate has been isolated from two different Claviceps purpurea strains. A purification of about 142‐fold was achieved by ammonium sulfate fractionation and the use of Sepharose 6B and DEAE‐Sepharose CL‐6B columns. The purified enzyme requires thiamine pyrophosphate and a divalent metal ion (Mn 2 + or Mg 2 +) for maximum activity but no FAD. The optimum pH is about 6.0 and the optimum temperature is 40 °C. The enzyme is not inhibited by branched‐chain amino acids neither singly nor in combination. AHAS is strongly inhibited by p ‐chloromercuribenzoate and N‐ethylmaleimide. The apparent K m values for pyruvate and TPP are 1.7 × 10 −2 M and 1.2 × 10 −6 M , respectively.