Lysis

About: Lysis is a research topic. Over the lifetime, 6072 publications have been published within this topic receiving 216978 citations.

Cell structure and the enzymic lysis of bacteria.

Abstract: SUMMARY: Untreated cells of three Gram-negative and four Gram-positive bacteria were resistant to lysis by crude and crystallbe trypsin. The resistance of the Gram negative organisms to lysis by trypsin was abolished by heating suspensions for 5 min. at 100°; the rates and extent of lysis of the three organisms by crude trypsin were comparable. After maximal lysis of heated suspensions of Bacterium coil and Pseudomonas fluorescens, by crude trypsin, examination of the residual material in the electron microscope showed that cel walls were the principal components. When heated suspensions of Micrococcus lysodeikticus, Bacillus megaterium and Staphylococcus aurm were incubated with crude or crystalline trypsin, slow lysis occurred and the extent of lysis was less than that observed for the Gram-negative bacteria. Electron microscopic examination of trypsin-lysed cells of B. megMum showed incomplete digestion of cytoplasmic contents. Heated and autochved cells of Streptococcus faecalis were resistant to digestion with trypsin. Cell-wall suspensions of B. meguterium were rapidly lysed on incubation with crystalline lysozyme. Heated cells of M. lysodeikticus were only partially lysed by lysozyme, but the subsequent addition of trypsin resulted in a rapid dissolution of the cell bodies. Although treatment of heated B. megaterium cells with lysozyme resulted in turbidity increases, the enzyme completely digested the cell wall leaving coagulated protoplasmic bodies. The protoplasmic bodies were rapidly lysed by crude trypsin.

Isolation and Characterisation of Insulin Secretory Granules from a Rat Islet Cell Tumour

Abstract: Density gradient centrifugation techniques, using iso-osmotic colloidal silica suspensions (Percoll), were developed for the isolation of insulin secretory granules from a transplantable rat islet cell tumour. These procedures were readily completed within 7 h and from each animal yielded approximately 1 mg of granule protein. The isolated granules were essentially free of other subcellular organelles as evaluated by their contents of marker proteins, electron microscopy and by electrophoretic analyses. Their susceptibilities to lysis at low osmotic strength, at pH values above 7 or in media containing sodium ions were similar to those of granules partially purified from islets. Insulin comprised 50-60% of the total granule protein when determined by immunoassay or by densitometry of electrophoretic profiles. The proinsulin content was marginally higher than that of islets, as was the ratio of insulins I to II. Electrophoretic analyses revealed that the secretory granules contained 150 or more proteins besides insulin-related peptides. The majority of these had acidic isoelectric points and were located both within the granule interior and its enveloping membrane.

Baseplate protein of bacteriophage T4 with both structural and lytic functions.

Abstract: Analyses of a new bacteriophage T4 mutant that permits lysis of infected cells in the absence of e lysozyme showed that the strain carried a suppressor mutation in gene 5, a gene whose polypeptide product (gp5) is an integral component of the virion baseplate. Indirect experiments indicated that cell lysis was caused by the lytic action of mutant gp5. With regard to the physiological role of normal gp5, we speculate that it functions in the initiation of infection by catalyzing local cell wall digestion to facilitate penetration of the tail tube through the cell envelope. The proposed lytic activity of gp5 may also be responsible for the well-known phenomenon of lysis from without observed with T4.