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Substrate Specificity and Some Physicochemical Properties of Autolytic Enzymes of the Bacterium Lysobacter sp. XL 1

I. M. Tsfasman, B. V. Sitkin, V. Ya. Lysanskaya, O. A. Stepnaya*, and I. S. Kulaev

Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, pr. Nauki 5, 142290 Pushchino, Moscow Region, Russia; fax: (495) 923-3602; E-mail: stepnaya@ibpm.pushchino.ru; kulaev@ibpm.pushchino.ru

* To whom correspondence should be addressed.

Received April 12, 2007
The substrate specificity of autolytic enzymes of the bacterium Lysobacter sp. XL 1 has been established. The periplasmic enzyme A8, the cytosolic enzyme A1, and the enzyme A10 solubilized from the cell walls and membranes with Triton X-100 exhibit glucosaminidase activity; the cytosolic enzyme A4 and the enzyme A9 solubilized from the cell walls and membranes with LiCl exhibit the muramidase activity. The cytosolic enzymes A3 and A6 have N-acetylmuramoyl-L-alanine amidase activity, and the enzyme A5 exhibits the diaminopimelinoyl-alanine endopeptidase activity. Some physicochemical properties of the most active autolytic cytosolic enzymes of Lysobacter sp. XL 1 (endopeptidases A5 and A7 and N-acetylmuramoyl-L-alanine amidase A6) were studied. The enzymes exhibit maximal activity over a wide range of buffer concentrations in weakly alkaline medium and moderate temperatures. The investigated enzymes are comparatively thermolabile proteins.
KEY WORDS: autolytic enzymes, peptidoglycan, substrate specificity, physicochemical properties

DOI: 10.1134/S0006297907070103