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Isolation and Characterization of a New Extracellular Bacteriolytic Endopeptidase of Lysobacter sp. XL1


O. A. Stepnaya1*, I. M. Tsfasman1, I. A. Logvina1, L. P. Ryazanova1, T. A. Muranova2, and I. S. Kulaev1

1Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, 142292 Pushchino, Moscow Region, Russia; fax: (7-095) 923-3602; E-mail: Stepnaya@ibpm.pushchino.ru

2Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; fax: (027) 790-527; E-mail: Muranova@fibkh.serpukhov.su

* To whom correspondence should be addressed.

Received October 6, 2004; Revision received December 16, 2004
The previously unstudied bacteriolytic enzyme L4 was isolated from the culture liquid of the bacterium Lysobacter sp. XL1 in electrophoretically homogeneous state. The enzyme L4 is a diaminopimelinoyl-alanine endopeptidase relative to peptidoglycan of Lysobacter sp. XL1. The enzyme is an alkaline protein of ~21 kD. The N-terminal amino acid sequence of the enzyme has been determined -- A V V N G V N Y V Gx T T A ... The maximal activity of the enzyme was observed in 0.05 M Tris-HCl at pH 8.0 and 50-55°C. The half-inactivation temperature of the enzyme is 52°C. The endopeptidase L4 is not a metalloenzyme since it is not affected by EDTA. The enzyme is inhibited by p-chloromercuribenzoic acid by 72% and by phenylmethylsulfonyl fluoride by 43%, which indicates the involvement of serine and thiol groups in its functioning.
KEY WORDS: bacteriolytic enzyme, Lysobacter sp., lysoamidase, purification, properties