PubMed Health⌕ Search

Biomedical subjects

P J Müller

Publications and source records attributed to P J Müller.

At least 19 recordsLinked to original sources
PubMed2000

Complementary characterization of a hyaluronic acid splitting enzyme from Streptococcus agalactiae.

A hyaluronic acid splitting enzyme of Streptococcus agalactiae was characterized by splitting mechanism, Michaelis-constant and inhibition type for sulfated hyaluronic acid: The enzyme splits hyaluronic acid as a hyaluronate lyase [EC 4.2.2.1]. The Km = 8 x 10(-4) mg ml-1 was determined with the influence of substrate inhibition constant Kiu = 2 x 10(-6) mg ml-1. Sulfated hyaluronic acid inhibits the enzyme in a partially non-competitive way. The inhibition constant is Ki = 5.47 x 10(-4) mg ml-1. The GBS-hyaluronate lyase cleaves hyaluronic acid as an endoglycosidase. The work is related with the intention to establish a hyaluronate lyase of microbial origin as a therapeutical enzyme replacing bovine hyaluronidase.

Animals↗
PubMed1998

Influence of the phosphorylation state on the biological activity of a low-molecular mitogen from group A streptococci.

A low molecular weight mitogen (LMP) from Streptococcus pyogenes strain NY 5 was successively purified by adsorption on phenylsepharose, chromatography on Resource S and Superdex G 30 and finally by affinity chromatography on antiphosphothreonine agarose. The N-terminal protein sequence of the mitogen was determined. The occurrence of phosphoamino acids was investigated by immunoassay using monoclonal antibodies. The LMP is a threonine-phosphorylated protein different of HPR protein of PTS-system, its mitogenic activity was lost after treatment with streptococcal protein phosphatase or alkaline phosphatase. The inactivated LMP was activated by phosphorylation with phosphokinase and ATP. The active LMP was also inactivated in streptococcal cultures secreting acid protein phosphatase during the phase of phosphate limitation.

Adenosine Triphosphate↗
PubMed1994

Kinetics of growth and product formation in cultures from streptococci of groups A and C.

During growth of streptococci of Lancefield groups A and C in a culture medium containing glucose, yeast extract and peptone, two main growth phases occur: growth phase I and growth phase II (diauxic growth). They are separated by a short stationary phase (1st stationary phase). The diauxic growth is caused by transient limitations as well as the availability of new sources of the amino acids L-serine and L-arginine. Growth phase I consists of an exponential and a nearly linear part. These growth kinetics are reflected by the kinetics of gas metabolism as well as by product formation. Hyaluronic acid is formed during the nearly linear phase whereas the enzyme alkaline phosphatase, is exclusively excreted in the 1st stationary phase. Also carbon dioxide and L-lactate are mainly produced in a growth phase-dependent mode. In the late stationary phase (2nd stationary phase) more oxygen is consumed whereas the demand for oxygen in the 1st stationary phase is nearly zero.

Amino Acids↗
PubMed1993

Metabolism of phosphate-limited cultures of Streptomyces. IV. Protein-phosphorylation of antibiotics-producing cultures.

It has been demonstrated that in the cellular proteins of Streptomyces hygroscopicus JA 6599 and Streptomyces noursei JA 3890 b, the producers of the antibiotics turimycin and nourseothricin, respectively, phosphorylated proteins are present. Numbers and concentrations of phosphorylated proteins decreased during the idiophase as characterized by phosphate limitation, antibiotic biosynthesis and phosphatase formation. Phosphoamino acids of serine, threonine and tyrosine were found in the hydrolysates of proteins. Protein tyrosyl kinase was demonstrated in the cellular extracts. The results supports the hypothesis that protein phosphorylation possesses a function in the regulation of growth and secondary product formation.

Bacterial Proteins↗
PubMed1992

[Bristle anchoring and bristle end-rounding in adults' toothbrushes].

Scanning electron microscopic study of bristle heads of 8 toothbrush brands commercially available in the Federal Republic of Germany and Switzerland has shown qualitative variations in the rounding of bristle ends. The percentage of acceptable end rounding of the bristles was for 4 brands above 75% and for 2 brands 55-56%. For 2 products, the percentage was below 40%. The new method of welding bristle bundles at their base into the head of the toothbrush was used only by one producer.

Adult↗
PubMed1985

[Metabolism of phosphate-limited Streptomyces cultures. III. The ambivalent effect of phosphates in nourseothricin-producing cultures of Streptomyces noursei JA 3890b].

A common condition in the evolution of organisms and their metabolism seems to be a latent lack of available phosphate in the natural environment. Accordingly, the phosphate dependent metabolisms of the soil-living streptomycetes should be stamped by lack of phosphate, too. The biosynthesis of the streptothricin antibiotic nourseothricin by Streptomyces noursei 3890b is initiated by limitation of soluble phosphate in the fermentation medium. At the other side is shown that a certain rate of feeding of phosphate during the fermentation increases the nourseothricin biosynthesis. An ambivalente role of phosphate on the secondary metabolite biosynthesis is stated. The limitation of phosphate leads to a special physiological state of the producer, characterized by secondary product formation and dephosphorylating activities in cells. This state is temporally stabilized by the presence of a sufficient phosphate supply, realized by enzymatic hydrolysis of complex phosphate-containing substrates or by a direct feeding of inorganic phosphate to the fermentations. The occurrence of different physiological states in respect to the phosphate-dependent metabolism is described by S-shaped functions of the relationship between specific growth rate and the phosphate concentration in the medium. The special behaviour of Streptomyces noursei cells at phosphate limitation is discussed to be the result of the dephosphorylating activities in cells, hydrolyzing phosphoester-bonds of regulatory metabolites as well as energy-rich compounds.

Anti-Bacterial Agents↗
PubMed1984

Effect of phosphate on the biosynthesis of nourseothricin by Streptomyces noursei JA 3890b.

The results present evidence for the important role of phosphate-mediated regulation of the nourseothricin biosynthesis by the processes of phosphate limitation and release of phosphate. Also, higher initial concentrations of phosphate were found to have a strong inhibitory effect on the biosynthesis of nourseothricin. It is concluded that the initial phosphate concentration was the primary target for the biometrical optimization of the fermentation medium. The presence of zinc ions neutralized the negative effect of high initial concentrations of phosphate which was also strongly influenced by the regime of sterilization.

Anti-Bacterial Agents↗
PubMed1984

[Metabolism of phosphate-limited Streptomyces cultures. I. Purification and characterization of alkaline phosphatase produced by Streptomyces hygroscopicus].

Alkaline phosphatase from Streptomyces hygroscopicus strain JA 5999-R 27-158 was purified and characterized. The enzyme was found in the culture filtrate and in the mycelium. The phosphatase was extracted from the mycelium and purified by adsorption to DEAE-cellulose. To separate impurities, the crude enzyme solution was heated and the phosphatase purified by chromatography through CM-Sepharose and Sephadex G 100. The specific activity of the resulting enzyme was 1000 microMol/min/mg at 25 degrees C. The molecular weight determined by SDS gel electrophoresis was found to be 56 000. The Michaelis-Menten constant determined with p-nitrophenylphosphate as substrate was Km = 1.25 X 10(-3) M. Phosphatase activity was dependent on the presence of Ca++ and the maximum activity of enzyme with p-nitrophenylphosphate as substrate was found at pH 9.2. The pI as detected by isoelectric focusing was at pH 5.6. Temperatures from 30 degrees to 75 degrees C did not affect the stability of the enzyme. The alkaline phosphatase exhibited high substrate specificity; of various phosphomonoesters tested, only p-nitrophenylphosphate, methylumbelliferyl-phosphate, phosphoenolpyruvate, ADP, ATP and tyrosine-O-phosphate was hydrolysed. The activity was inhibited by NAF, Na2P2O7 and EDTA. The involvement of the alkaline phosphatase in the regulation of secondary metabolism was discussed.

Alkaline Phosphatase↗
PubMed1984

[Metabolism of phosphate-limited Streptomyces cultures. II. Purification and characterization of acid phosphatase from culture filtrates of turimycin-producing Streptomyces hygroscopicus].

Acid phosphatase was purified from culture filtrates of Streptomyces hygroscopicus strain JA 6599-R 27/158. Method used included as first step either ammonium sulfate precipitation or adsorption of acid phosphatase on Bentonit and the desorption of enzyme from Bentonit with alkaline buffers, adsorption to DEAE-cellulose, column chromatography on Sephadex G 50 and isoelectric focusing in Sephadex gel. The specific activity of the resulting enzyme was 51 muMol/min/mg at 25 degrees C and pH of 6.25 with p-nitrophenylphosphate as substrate. The pI detected by isoelectric focusing was at pH 7.25. The molecular weight determined by gel chromatography and by SDS electrophoresis was found to be 27 000. The pH-dependence of hydrolytic activity of acid phosphatase was substrate specific. The enzyme was found to hydrolyze essentially at pH 6.2 phosphoenolpyruvate, ATP, ADP, fructose-1,6-diphosphate and tyrosine-O-phosphate. The activity was inhibited by phosphate, molybdate, arsenate, vanadate, pyrophosphate and tetraborate. In the culture medium the acid phosphatase caused the release of phosphate from solid and soluted substrates. Therefore the involvement of acid phosphatase in the regulation of secondary metabolism was discussed.

Acid Phosphatase↗
PubMed1983

Regulation of hydrolase formation and phosphate release in turimycin fermentations.

During the turimycin fermentation hydrolytic enzymes are excreted responsible for orthophosphate release from phosphate-containing dissolved and undissolved complex medium constituents. Following a phosphate-limited growth period the phosphate release leads to a second growth period (diauxic growth). Depending on the rate of phosphate release the length of the lag phase of diauxic growth changes in different fermentations. The resulting second growth period is correlated with a transient delay in the formation of turimycin, of phosphatases and of nucleases. The amylolytic activities are formed already within the first hours after the beginning of fermentations. Phosphatases, nucleases and protease are excreted parallel to turimycin formation after extracellular phosphate limitation in presence of ammonia and glucose. A special role of phosphate limitation initiating enzyme synthesis is proposed.

Deoxyribonucleases↗
PubMed1983

Sequential processes of phosphate limitation and of phosphate release in streptomycin fermentations.

The significance of the sequential processes of phosphate limitation and of phosphate release from medium constituents is demonstrated in technical streptomycin fermentations. The phosphate limitation initiated the streptomycin synthesis as well as the formation of phosphatases and protease. In later periods of the process the phosphate release influences especially the enzyme formation.

Culture Media↗
PubMed1983

Parallel regulation of cAMP phosphodiesterase and phosphatase activities in turimycin fermentations.

Phosphate limitation induces the turimycin biosynthesis as well as the cAMP phosphodiesterase and phosphatase. The results are discussed in connection with the observation of general high activities of dephosphorylating enzymes and low concentrations of phosphorylated intermediates under conditions of phosphate limitation and secondary product biosynthesis, respectively.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1983

Uncoupling of respiration in turimycin fermentations.

Results furnish evidence for a partial uncoupling of respiration at conditions of phosphate limitation in turimycin fermentations. The uncoupling was primarily caused by the high intracellular ATP hydrolase activity and probably also by the CN-resistant respiration. The results support the idea that high dephoshorylating enzyme activities may have a regulatory effect on the secondary product biosynthesis.

Cytochromes↗
PubMed1982

Bistability in the glucose and energy metabolism of ammonia-limited chemostat cultures of Escherichia coli ML 30.

Recently bistability in the pyruvate production of ammonia-limited glucose-grown Escherichia coli ML 30 chemostat cultures was evidenced. The present investigation shows that the state of higher pyruvate production is connected with a lower glycogen content than in cells in the state of lower pyruvate production. The results support the view of a regulation of bistability on the step of pyruvate consumption by the citric acid cycle. Pronounced differences in energy formation in the two states of glucose bistability are discussed.

Ammonia↗