Tryptophan Indole-Lyase from Proteus vulgaris: Kinetic and Spectral Properties

L. N. Zakomirdina¹, V. V. Kulikova¹, O. I. Gogoleva², I. S. Dementieva¹, N. G. Faleev^2*, and T. V. Demidkina^1*

¹Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, ul. Vavilova 32, Moscow, 119991 Russia; fax: (095) 135-1405; E-mail: TVD@genome.eimb.relarn.ru

²Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, ul. Vavilova 28, Moscow, 117813 Russia; fax: (095) 135-5085; E-mail: ngfal@ineos.ac.ru

^* To whom correspondence should be addressed.

Received April 17, 2002; Revision received June 6, 2002

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An efficient method for purification of recombinant tryptophanase from Proteus vulgaris was developed. Catalytic properties of the enzyme in reactions with L-tryptophan and some other substrates as well as competitive inhibition by various amino acids in the reaction with S-o-nitrophenyl-L-cysteine were studied. Absorption and circular dichroism spectra of holotryptophanase and its complexes with characteristic inhibitors modeling the structure of the principal reaction intermediates were examined. Kinetic and spectral properties of two tryptophanases which markedly differ in their primary structures are compared. It was found that although the spectral properties of the holoenzymes and their complexes with amino acid inhibitors are different, the principal kinetic properties of the enzymes from Proteus vulgaris and Escherichia coli are analogous. This indicates structural similarity of their active sites.

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KEY WORDS: tryptophan indole-lyase from Proteus vulgaris, pyridoxal-5´-phosphate, purification, substrates, inhibitors, spectral properties

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