Proteinous Bacterial Cell Wall Lytic Enzyme Inhibitor Produced by Bacteria

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A bacterium (No.SMK-6024) which produced N-acetylmuramidase inhibitor was isolated from soil. This strain was identified as Bacillus megaterium. The inhibitor was purified by ammonium sulfate fractionation, SP-Sephadex column chromatography and Sephacryl S-200 gel filtration. The inhibitor was named as LEI. LEI inhibited N-acetylmuramidase from Streptomyces but did not inhibit lysozyme from animal and plant origin. Molecular weight of LEI was estimated as 32,000 by gel filtration and as 16,000 by SDSPAGE. This indicated that LEI consisted of dimer. Isoelectric point was 6.7. EI complex exsisted as E_2I_2.A bacterium (No.I-139) which produced egg white lysozyme inhibitor was isolated form soil. The inhibitor was purified by ammonium sulfate fractionation, column chromatography by DEAE-Sephadex, Sephacry S-200 or DEAE-Toyopearl, and affinity chromatography by immobilized egg white lysozyme. The inhibitor was named as I-139 I-139 inhibited animal lysozyme such as egg white lysozymes and human milk lysozyme, but did not inhibit plant lysozyme and N-acetylmuramidase from microbilal origin. Purified I-139 contained lipid. This lipid was removed by organic solvent. The molecular weight of this inhibitor was estimated as 14,000. Leu, Asp, Val and Glu were main amino acids in the inhibitor.