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The present paper reports a modified method for isolation of lysostaphin--a bacteriolytic agent with specific affinity for staphylococcal cell wall. The proposed purification scheme includes three steps. The first procedure is ultrafiltration through a membrane filter giving a yield of 75.6%. The result of ultrafiltration is a concentrated, 10-times purified preparation of lysostaphin with specific activity 0.62 U/mg which can be used for digestion of S. aureus cells. Further step, performed by ion-exchange chromatography on DEAE-cellulose, yields a 60-times purified preparation containing a mixture of enzyme components of lysostaphin. The yield of this step is 47.2%, the preparation contains 3.54 U/mg protein. Using gel filtration on Sephadex G-50 a component with hexosaminidase activity was separated from the endopeptidase component on the basis of molar mass difference. A 270-times purified preparation of lysostaphin-endopeptidase with minimum of contaminating substances was obtained in this step. The yield of gel filtration was 22.1%, specific activity increased up to 16.3 U/mg protein.

In quinone-depleted mitochondrial and Paracoccus denitrificans membranes the quantum yield of fluorescence of ostruthin (6-geranyl-7-hydroxycoumarin) was maintained, whereas an increase in the quantum yield took place after extraction of Staphylococcus epidermidis membrane. A marked quenching effect of ubiquinone and menaquinone each with two isoprene units in the side chain on the ostruthin fluorescence was found with all types of quinone-depleted particles. When the homogues of menaquinone and ubiquinone with six isoprene units in the side chain were re-incorporated, a quenching of the ostruthin fluorescence was observed in the S. epidermidis membranes but not in those of P. denitrificans. The different behaviour of both bacterial preparations is attributable to the more specific finding of ubiquinone in the particles of P. denitrificans.