deoxycholic-acid and Autolysis

Topics: Animals; Antibody Formation; Antigen-Antibody Reactions; Autolysis; Carbohydrates; Cell Membrane; Cell-Free System; Chemical Phenomena; Chemistry; Deoxycholic Acid; Epitopes; Genotype; Graft Rejection; Guinea Pigs; Histocompatibility Antigens; Humans; Hypersensitivity, Delayed; Immunologic Techniques; Mice; Microscopy, Electron; Papain; Proteins

The native molecular forms of acetylcholinesterase (AChE) present in adult Drosophila heads were characterized by sedimentation analysis in sucrose gradients and by nondenaturing electrophoresis. The hydrophobic properties of AChE forms were studied by comparing their migration in the presence of Triton X100, 10-oleyl ether, or sodium deoxycholate, or in the absence of detergent. We examined the polymeric structure of AChE forms by disulfide bridge reduction. We found that the major native molecular form is an amphiphilic dimer which is converted into hydrophilic dimer and monomer on autolysis of the extracts, or into a catalytically active amphiphilic monomer by partial reduction. The latter component exists only as trace amounts in the native enzyme. Two additional minor native forms were identified as hydrophilic dimer and monomer. Although a significant proportion of AChE was only solubilized in high salt, following extractions in low salt, this high salt-soluble fraction contained the same molecular forms as the low salt-soluble fractions: thus, we did not detect any molecular form resembling the asymmetric forms of vertebrate cholinesterases.

Topics: Acetylcholinesterase; Animals; Autolysis; Centrifugation, Density Gradient; Chemical Phenomena; Chemistry, Physical; Deoxycholic Acid; Disulfides; Dithiothreitol; Drosophila melanogaster; Electrophoresis, Polyacrylamide Gel; Macromolecular Substances; Mercaptoethanol; Octoxynol; Oxidation-Reduction; Plant Oils; Polyethylene Glycols

Topics: alpha-Glucosidases; Animals; Autolysis; Chromatography, Gel; Deoxycholic Acid; Dextrins; Freezing; Intestinal Mucosa; Oligo-1,6-Glucosidase; Papain; Polyethylene Glycols; Solubility; Sonication; Sucrase; Swine

During penicillin treatment of an autolysin defective mutant pneumococcus we have observed three novel phenomena: (i) Growth of the mutant cultures is inhibited by the same concentrations of penicillin that induce lysis in the wild type. (ii) Mutant bacteria treated with the minimum growth inhibitory concentration of penicillin will lyse upon the addition of wild-type autolysin to the growth medium. Chloramphenicol and other inhibitors of protein synthesis protect the cells against lysis by exogenous enzyme. Sensitivity of the cells to exogenous autolysin requires treatment with penicillin or other inhibitors of cell wall synthesis (e.g., D-cycloserine or fosfonomycin) since exogenous autolysin alone has no effect on bacterial growth. (iii) Treatment with penicillin (or other inhibitors of cell wall synthesis) causes the escape into the medium of a choline-containing macromolecule that has properties suggesting that it contains pneumococcal lipoteichoic acid (Forssman antigen). Each one of these three phenomena (growth inhibition, sensitization to exogenous autolysin, and leakage of lipoteichoic acid) shows the same dose response as that of the penicillin-induced lysis of wild-type pneumococci. On the basis of these findings we propose a new hypothesis for the mechanism of penicillin-induced lysis of bacteria. It is suggested that inhibition of cell wall synthesis by any means triggers bacterial autolytic enzymes by destabilizing the endogenous complex of an autolysin inhibitor (lipoteichoic acid) and autolytic enzyme. Escape of lipoteichoic acid-like material to the growth medium is a consequence of this labilization. Chloramphenicol protects bacteria against penicillin-induced lysis by interfering with the activity of the autolytic enzyme, rather than by depleting the concentration of the enzyme at the cell surface.

Topics: Autolysis; Cell Wall; Chloramphenicol; Deoxycholic Acid; Enzyme Activation; Penicillins; Streptococcus pneumoniae; Teichoic Acids; Time Factors