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Extracellular culture filtrates from ligninolytic cultures of the lignin-degrading basidiomycete Lentinula (syn. Lentinus) edodes (Berk.) Pegler contained one major peroxidase when grown on a commercial oak-wood substrate. The peroxidase was purified by polyethylenimine clarification, anion-exchange chromatography, and hydrophobic-interaction HPLC. The enzyme (MnP1) was a heme-iron protein with an apparent molecular weight of 44,600 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels and an isoelectric point of pH 3.2. The native enzyme had an absorption maximum at 407 nm, which shifted to 420 nm upon H2O2 addition. The pyridine-hemochrome-absorption spectrum indicated that one heme group was present per enzyme as protoporphyrin IX. N-Terminal amino acid sequencing showed that MnP1 had higher sequence homology with manganese peroxidases than with lignin peroxidases reported from Phanerochaete chrysosporium. L. edodes MnP1 was capable of oxidizing lignin and lignin-model compounds in the presence of manganese and H2O2.

SUMMARYThe chemical compositions of the cell walls of one strain each of Bacillus stearothermophilus and B. coagulans prepared from organisms grown a t 37" and 55" are compared. The higher temperature of cultivation resulted-in an increased proportion of mucopeptide and a decreased proportion of teichoic acid in the walls of both organisms. A higher lipid content than is usual in Gram-positive organisms was found in these walls. The teichoic acid from B. stearothermophilus walls was a glycerophosphate polymer substituted with glucose and alanine ; evidence suggesting the presence of 2,3-phosphodiester linkages in this polymer is presented. The teichoic acid from B. coagulans walls was also a glycerophosphate polymer, substituted with two neutral sugars, glucose and galactose, but lacking amino acid substituents hitherto reported as characteristic of teichoic acids.

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The effects of three membrane-active agents, filipin, digitonin, and polymyxin B on the plasma membrane of ram spermatozoa have been studied by freeze-etch electron microscopy. Filipin and digitonin both reacted with cholesterol and caused visible membrane modification in cholesterol-rich regions, with filipin being a more specific agent than digitonin. Polymyxin B, which is known to interact specifically with negatively charged phospholipids of bacterial membranes, exhibited a selective binding and subsequent modification of sperm plasma membranes. This binding was shown to be inhibited in the presence of 1 mmol/1 Ca2+. We hence propose that both filipin and polymyxin B are useful cytological markers for specific biological molecules in eukaryote membranes--filipin for cholesterol, and polymyxin B for negatively charged phospholipids.