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The SI secondary alkylsulphohydrolase of the detergent-degrading micro-organism, Pseudomonas C12B, was separated from other alkylsulphohydrolases and purified to homogeneity. Under the experimental conditions used the enzyme completely hydrolysed D-octan-2-yl sulphate (D-1-methylheptyl sulphate), but showed no activity towards the corresponding L-isomer. Additional evidence has been obtained to indicate that it is probably optically stereospecific for D-secondary alkyl sulphate esters with the ester sulphate group at C-2 and with a chain length of at least seven carbon atoms. Enzyme activity towards racemic samples of heptan-2-yl sulphate (1-methylhexyl sulphate), octan-2-yl sulphate and decan-2-yl sulphate (1-methylnonyl sulphate) increased with increasing chain length. L-Octan-2-yl sulphate is a competitive inhibitor of the enzyme, as are certain primary alkyl sulphates and primary alkanesulphonates. Inhibition by each of the last two types of compounds is characteristic of the behaviour of an homologous series. Inhibition increases with increasing chain length and plots of log K1 values against the number of carbon atoms in each alkyl chain show the expected linear relationship. A crude preparation of the S2 secondary alkylsulphohydrolase was used to show that this particular enzyme hydrolyses L-octan-2-yl sulphate, but is probably inactive towards the corresponding D-isomer. The similarity of the SI and S2 enzymes to the CS2 and CS1 enzymes respectively of Comamonas terrigena was established, and some comments have been made on the possible roles of these and other alkylsulphohydrolases in the biodegradation of detergents.

ABSTRACT:The colonization of medical devices by micro-organisms is an ongoing problem, particularly as many strains of bacteria are becoming resistant to antibiotics. One method by which this could be addressed is the production of a surface that will kill bacteria on contact without releasing the disinfecting agent into solution. Self-disinfecting surfaces were prepared in which a quaternary ammonium salt was covalently bound onto a polyethylene film by a stable linkage. To achieve this, a low-density polyethylene film was treated with glow discharge followed by the graft polymerization of acrylic acid. The acid chloride derivative was then prepared. ␣,-Dibromoalkanes of various chain lengths were reacted with potassium phthalimide to form an N-alkylphthalimido group, and this was followed by an excess of piperidine to produce a tertiary amino group at the opposite end of the alkyl chain. The hydrolysis of the phthalimido group produced a primary amino function that was coupled to the grafted poly(acryl chloride). A reaction with octadecyl bromide resulted in the production of a quaternary ammonium salt. The amide linkage by which the quaternary ammonium salt was attached to the polymer was stable, and no release of the disinfecting moiety took place in solution. Soluble compounds containing a similar quaternary ammonium function were prepared through the reaction of the primary amine group with acetyl chloride rather than the polymeric acid chloride to form substituted Nacetamides. In a microbiological pilot study, both the polymer-bound and soluble quaternary ammonium salts were effective against suspensions of Staphylococcus aureus, Escherichia coli, and Saccharomyces cerevisiae. The results show that a self-disinfecting surface can be produced in which the quaternary ammonium function is an effective bacteriocide that remains bound to the polymer surface. In addition, the materials were toxic to a mammalian cell line (Chinese hamster ovary cells).

Studies on the effect of pH and ionic strength upon the activity of purified bovine testicular hyaluronidase have shown that the pH optimum for the hydrolysis of hyaluronic acid occurs at 5.2 in the presence of, and at 6.0 in the absence of NaCl. Hydrolytic activity towards various mucopolysaccharide and hyaluronate octasaccharide substrates was dependent upon the presence of strong electrolyte (LiCl, NaCl, KCl, CsCl, NaNO3 and Na2SO4), maximum activity being obtained at electrolyte strengths of 0.2. Identical weights of sulphated and unsulphated mucopolysaccharides were hydrolysed at similar rates under optimal conditions, except that double chains of chondroitin 4-sulphate were hydrolysed at twice the rate of the other polysaccharides. Hydrolytic activity towards hyaluronate hexasaccharide was favoured at pH values below 5.2 whereas transglycosylation activity was favoured at higher pH. Hyaluronate tetrasaccharide was neither a substrate for the hydrolytic or transglycosylation activity, nor was it an inhibitor of the enzymic hydrolysis of hyaluronic acid. No conformational change in hyaluronic acid was detected by CD-spectroscopy in the presence of varying concentrations of salt and the collective results suggest that the salt effect is exerted on the enzyme rather than on the substrate.