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At least 199 records · Page 11Linked to original sources
PubMed2005

Stabilization of cold-adapted protease MCP-01 promoted by trehalose: prevention of the autolysis.

Protease MCP-01 is similar to other cold-adapted enzymes in that it is a cold-adapted serine protease having high specific activity and low thermostability at low and moderate temperature. Its thermolability and self-autolysis has resulted in difficulties in its purification, preservation and research on its structure and function. The disaccharide trehalose is known to effectively stabilize proteins. Its prevention effect on the autolysis of cold-adapted protease MCP-01 was monitored by capillary electrophoresis. In the absence of trehalose, protease MCP-01 autolyzed rapidly at 35 degrees C. However, when trehalose was added, autolysis was remarkably prevented and the loss of activity reduced. MCP-01 may be a useful model for basic research on the interaction of protein and trehalose.

Electrophoresis, Capillary↗
PubMed1990

Increased resistance of the cardiac sarcoplasmic reticulum Ca(2+)-pump to autolysis after adaptation of rats to stress.

Experiments on rats are reported in which Ca2+ uptake by the sarcoplasmic reticulum (SR) and the time course of SR Ca(2+)-pump inactivation and Ca2+ leakage from intracellular compartments into the incubation medium were studied in tissue homogenates stored at 4 degrees C. Long-term (6 h) immobilization stress significantly reduced the ability of the SR to take up Ca2+, accelerating (two- to threefold) both Ca(2+)-pump inactivation and Ca2+ leakage induced by autolysis during storage. A course of adaptation to repeated short-term stress prevented the adverse effects of long-term stress on the SR Ca(2+)-pump. Adaptation to repeated stress itself accelerated the rate of Ca2+ uptake by the SR and sharply inhibited the SR Ca(2+)-pump inactivation and Ca2+ leakage induced by autolysis. Possible mechanisms for the adaptive stabilization of SR membranes against factors that cause autolysis are discussed.

Adaptation, Physiological↗
PubMed1988

[Calpain II of rabbit skeletal muscle. Regulation of enzymatic activity: influence of the presence of membrane phospholipids on enzymatic autolysis in the presence or not of substrate].

A calcium activated neutral proteinase (calpain II) was prepared on a large scale at a high degree of purity from rabbit skeletal muscle using an original purification procedure. "In vitro" highly purified Calpain II was optimally activated by 2 mM Ca2+ and had two subunits with a molecular weight of 80 kDa and 28 kDa. The influence of membrane acid phospholipids (phosphatidyl inositol PI, phosphatidyl serine PS) and neutral phospholipids (phosphatidyl choline) on calcium enzymatic autolysis in the presence or not of substrate was electrophoretically studied. In the absence of a substrate no degradation of the catalytic subunit (80 kDa) was observed: phosphatidyl inositol and phosphatidyl serine stimulated drastically the 28 kDa subunit degradation with a release of a common 18 kDa product. In the presence of substrate (beta-globin) the 28 kDa subunit was more protected against calcium autolysis. On the other hand, phosphatidyl serine seemed to induce simultaneously 80 and 28 kDa degradations: the released breakdown products were different from those obtained with phosphatidyl inositol and phosphatidyl choline. In presence or absence of substrate, phosphatidyl choline did not affect significantly the calpain II calcium autolysis. Further studies on calpain II-membrane binding as well as its influence on calpain - activity are in progress.

Animals↗
PubMed1985

Liberation of electrolytes during the induced autolysis of Aspergillus niger.

The induced autolysis of Aspergillus niger was studied by suspending mycelia in water; after 120 hours there was a 50% reduction in dry weight. The kinetics of the liberation of electrolytes during autolysis was studied, and a positive correlation was observed between the electrical conductivity of the autolizate and autolysis loss of mycelium dry weight.

Aspergillus niger↗
PubMedDate not supplied

[Lipids of rat myocardium in autolysis].

Alterations in lipid composition were studied by means of micro-thin-layer chromatography technique in rat myocardium during postmortal autolysis. Lipids of rat heart were stable enough at early periods of the autolysis. At the same time, the most labile fraction included phospholipids, polyglycerophosphatides and lecithins. The more stable fraction contained free cholesterol and neutral lipids. The main pathways of lipid degradation within the first 24 hrs of autolysis operated via hydrolysis of phospholipids, neutral lipids as well as via reactions of transacetylation and biotransformation (methylation etc).

Animals↗
PubMed1979

The development of mesosomes of Staphylococcus aureus during autolysis.

Mesosomes of Staphylococcus aureus were examined morphologically under the electron microscope. Three different methods of specimen preparation (thin section, freeze-fracture, and negative staining) were used to eliminate artifacts due to sample processing. Mesosomes were rarely seen in intact cells but were quite distinct in autolysed cells incubated in 1.2M sucrose -0.33M acetate buffer (pH 5.8) at 25 degrees C. The phospholipid content increased by 20% of the control as autolysis proceeded. Since the plasma membrane did not show any other significant changes, the development of mesosomes during autolysis was shown to be a real event. Most of the well-developed mesosomes were found at the septum in negatively stained specimens. Initial wall-lysis occurred at this site, suggesting a close relationship between autolysis and the development of mesosomes in S. aureus.

Bacteriolysis↗
PubMedDate not supplied

[Formation of resting cells in microbial suspensions undergoing autolysis].

Under experimentally selected conditions favoring spontaneous or induced autolysis of cell suspensions, the asporogenous bacteria Escherichia coli and Methylococcus capsulatus, the bacilli Bacillus cereus (under conditions of suppressed sporulation), and the yeast Saccharomyces cerevisiae were shown to be capable of forming cystlike resting cells. Their number was influenced by (1) cell density in the suspensions; (2) the presence of Ca2+ ions in nutrient-limited medium; (3) pH of medium; and (4) autolysis rate, dependent on the concentration of oleic acid (a chemical analogue of the autolysis-inducing d2 factor) introduced into the cell suspensions.

Bacillus cereus↗
PubMedDate not supplied

[Development of principles for the controlled autolysis of Escherichia and Salmonella].

The autolysis of Escherichia and Salmonella, depending on the conditions of the medium where the cultivation and lysis of the bacteria took place, was studied. The study revealed that the autolysis of these bacteria was most intensive if lysis was induced at the moment when the culture achieved the maximum specific growth rate, as well as in case when the extreme conditions were maintained in the medium during the autolytic process. Approaches to controlling the process of the induced autolysis of Escherichia and Salmonella were proposed and substantiated.

Bacteriolysis↗
PubMed1995

Improvement of thermal stability of subtilisin J by changing the primary autolysis site.

The thermostability of subtilisin J, an extracellular serine protease secreted from Bacillus stearothermophilus, has been improved by changing the primary autolysis site of the Asp-49 mutant protein. Previously we have shown that the Asp-49 mutant protein has proteolytic activity, but so unstable that it was primarily autolyzed in Tyr-58-Gln-59 peptide bond during cultivation (Jang et al. Biochim. Biophys. Acta. 1162, 233-235 1993). In the present study, to mitigate the autolytic degradation and increase the thermostability, we deleted the Tyr-58 residue using the Asp-49 mutant as a template. This mutant (Asp-49/delta Tyr-58 mutant) protein showed an improved resistance to heat treatment without changing the catalytic efficiency of the enzyme. These results show that change of primary autolysis site can stabilize the subtilisin.

Amino Acid Sequence↗
PubMed2002

Depolarization of the membrane potential by beta-lactams as a signal to induce autolysis.

The effect of beta-lactam antibiotics that are known to inhibit cell wall biosynthesis and induce cell wall autolysis on the electrophysiological state of the plasma membrane in Streptomyces griseus was studied. Addition of various beta-lactam antibiotics induced a dose- and growth-stage-dependent depolarization of the membrane potential of Streptomyces griseus. The hydrolyzed biologically inactive derivative penicilloic acid had no depolarizing effect on the membrane potential. The ionophore gramicidin D, while depolarizing the membrane potential, also induced a dose-dependent increase in cell wall lysis. These observations suggest that alteration of the transmembrane potential could be an important signal in triggering cell wall autolysis of S. griseus.

Anti-Bacterial Agents↗
PubMed1975

[Influence of autolysis on the immunohistology of tissue-bound immunglobulins in the kidney (author's transl)].

The influence of autolysis on the immunhistological detectability and the immunological properties of tissue-bound basement membrane antibodies were investigated in the rat kidney. The immunhistological demonstration of antibodies was not affected up to 3 days post mortem. The disturbing autofluorescence of the autolytic tissue can be avoided by using peroxydase labeled antibodies. Basement-membrane antibodies that were eluted from the kidneys after an autolysis period of 2 days showed a homogenous linear deposition in kidney basement membrane after reinjection into normal rats. Their antibody properties were not affected.

Animals↗
PubMed1995

Chemical and cytological changes during the autolysis of yeasts.

Cell suspensions of Sacharomyces cerevisiae, Kloeckera apiculata and Candida stellata were autolyzed in phosphate buffer, pH 4.5, for up to 10 days. Cell dry weights decreased by 25-35% after 10 days. Based on initial cell dry weight, the soluble autolysate consisted of: carbohydrate (principally polysaccharide) 3-7%; organic acids 3-6%; protein 12-13%; free amino acids 8-12%; nucleic acid products 3-5%; and lipids 1-2%. The main organic acids in autolysates were propionic, succinic and acetic and the main amino acids were phenylalanine, glutamic acid, leucine, alanine and arginine. Approximately 85-90% of cellular RNA and 25-40% of cellular DNA were degraded during autolysis. Both neutral lipid and phospholipid components were degraded, with neural lipids but not phospholipids being found in autolysates. Scanning and transmission electron micrographs showed retention of cell wall structure and shape during autolysis, but there was extensive intracellular disorganization within S. cerevisiae and C. stellata. There were differences in the autolytic behavior of K. apiculata compared with S. cerevisiae and C. stellata.

Amino Acids↗
PubMed1993

Biochemical, morphological and cytochemical studies of enhanced autolysis of Saccharomyces cerevisiae. 1. Biochemical studies.

Biochemical aspects of induced autolysis of Saccharomyces cerevisiae were observed in the presence of various physical and chemical enhancers of autolysis (increased temperature, changes of pH, NaCl, ethanol, fresh autolyzate). Direct assays of proteinases, nucleases, glucanases and acid phosphatases in homogenized autolyzed cells were performed. In addition, the degradation products of proteins, nucleic acids, polysaccharides and phosphate from phosphorylated compounds were determined in the supernatant of autolyzate after centrifugation. These results suggested that the inducers affected transport processes and that they had mostly negative effects on the activities of the above-mentioned enzymes.

Acid Phosphatase↗
PubMed1977

Ultrastructural and functional changes in pancreatic acinar cells during autolysis.

Effects of anoxemic cell injury on rat pancreatic acinar cells were studied in a preparation where tissue samples were incubated at temperature between 18-20 degrees C in a moist atmosphere for 0, 0.5, 1, 3, 6, 12, and 24 h in vitro. Electron microscopy revealed that disintegration of acinar cells began by swelling of various cell compartments and gradual breakdown of cell membranes. Zymogen granules remained morphologically intact for at least 3 h. There were no signs of increased autophagic activity during the period of observation. Myelin figures and other membranous remnants of disintegrated cells, together with individual cells and cell organelles whose morphology was relatively well preserved were seen even after w4 h incubation. The secretory response of acinar cells to pancreozymin stimulation, as measured by amylase release into the incubation medium in vitro, decreased progressively closer to zero during 12 h autolysis. No active trypsin could be detected in the tissue samples during the 24 h observation time. It was concluded that during hypoxic autolysis at room temperature between 18-20 degrees C in vitro: 1. Acinar cell disintegration results from breakdown of cellular membranes, 2. autophagocytosis is not involved, 3. most of zymogen granules remain morphologically intact even at the time when cell membranes show evidence of damage, 4. there is no trypsin activation taking place in the tissue, and 5. the acinar cells are capable of responding to secretory stimulation for 3 to 6 h after removal of the tissue from the experimental animal.

Amylases↗
PubMed1993

In situ autolysis of mouse brain: ultrastructure of mitochondria and the function of oxidative phosphorylation and mitochondrial DNA.

The effect of in situ autolysis on cerebral mitochondrial structure and function has been investigated. Mice (n = 9) were sacrificed and stored for up to 24 h under unfavorable post-mortem conditions at 25 degrees C. At different time intervals groups of three animals were submitted to post-mortem dissection and tissue from different regions of the brain was used for the preparation of "free" and synaptosomal mitochondria. On electron microscopic examination, the post-mortem period had no significant influence on mitochondrial morphology and enzymatic activities of complexes I-V of the mitochondrial oxidative phosphorylation system were still present in all the mitochondrial preparations from different regions of the brain, albeit at a reduced levels. Degradation of mitochondrial DNA was virtually absent from mitochondrial preparations during the 24-h period of autolysis, as shown by the presence of intact DNA by Southern blot and PCR analysis. Based on these results, alterations in mitochondrial DNA and deficiencies of mitochondrial respiratory complexes I-V can be recognized in cerebral tissue even after 24 h of unfavorable post-mortem storage conditions.

Animals↗
PubMed2003

Degradation of DNA during the autolysis of Saccharomyces cerevisiae.

The autolysis of yeast cells has practical implications in the production of fermented foods and beverages and flavourants for food processing. Protein and RNA degradation during yeast autolysis are well described but the fate of DNA is unclear. Yeast cells ( Saccharomyces cerevisiae) were autolysed by incubating suspensions at 30-60 degrees C (pH 7.0), and at pH 4.0-7.0 (40 degrees C) for 10-14 days. Up to 55% of total DNA was degraded, with consequent leakage into the extracellular environment of mainly 3'- and 5'-deoxyribonucleotides, and lesser amounts of polynucleotides. The rate and extent of DNA degradation, composition of the DNA degradation products and DNase activity were affected by temperature and pH. The highest amount of DNA degradation occurred at 40 degrees C and pH 7.0, where the highest DNase activity was recorded. DNase activity was lowest at 60 degrees C and pH 4.0, where the proportion of polynucleotides in the degradation products was higher.

Autolysis↗
PubMed1988

Acetylcholinesterase undergoes autolysis to generate trypsin-like activity.

Acetylcholinesterase (AChE) is one of the most highly studied enzymes, although its function in many tissues has remained obscure. AChE purified from eel or foetal bovine serum possesses proteolytic activity in addition to esterase activity. The presence of trypsin-like and metallocarboxypeptidase-like activities associated with AChE accounts for its ability to convert enkephalin peptide precursors into enkephalins. Several lines of evidence indicate that AChE's trypsin-like activity is an integral component of the molecule and that it is activated by autolysis. Incubation of affinity-purified eel AChE generated several fragments of low relative molecular mass (Mr). One of these low Mr fragments (Mr = 25,000 Da, 25K) cleaved from the 70K form of AChE, possessed considerable sequence similarity to the N-terminal sequence of pancreatic trypsin. Autolysis of eel AChE may give rise to a neuropeptide processing enzyme.

Acetylcholinesterase↗
PubMedDate not supplied

Changes in CNS myelin proteins and glycoproteins after in situ autolysis.

The effects of postmortem autolysis in situ on myelin proteins and glycoproteins were studied in 25- and 125-day-old mouse brain and in adult bovine brainstem. In bovine myelin a loss of the major myelin glycoprotein was the only difference observed when the tissue was left at 19 degrees C for 24 hours compared to immediately frozen material. In the autolysed mouse brain, the myelin major glycoprotein was the most affected component with a 55% decrease. Both myelin basic protein components were degraded with a 35% loss. The other myelin proteins did not change under the conditions used for this study. There was also no change in the specific activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase, a myelin-associated enzyme. Using the double labelling technique with [3H]fucose and [3 5S] sulfate as precursors injected intracranially, a shift of the major myelin glycoprotein labelled with radioactive sulfate towards a smaller apparent molecular size was observed as a result of the autolysis whereas the electrophoretic mobility of the fucose labelled major peak was unaffected.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗