Effect of temperature,salts, pH and other factors on the development of peritrichous flagella in Vibrio alginolyticus

The development of peritrichous flagella and, consequently, swarming of Vibrio alginolyticus depend on a complex relationship between temperature, salt concentrations and pH. At temperatures above 28°C V. alginolyticus did not develop peritrichous flagella unless certain minimal concentrations of NaCl are present: the higher the temperature, the higher the NaCl concentrations required for peritrichous flagella synthesis. This requirement for NaCl at high temperatures is much more pronounced at pH 9 than at pH 6. High temperatures and low concentrations of NaCl also inhibited swarming of cells already armed with peritrichous flagella. Other cations, such as Li⁺, K⁺ and Mg²⁺, replaced NaCl only at temperatures below 28°C.     

Effect of prodigiosin on the lysozyme activity in melioidosis]

Decreased lysozyme activity was observed under conditions of melioidosis intoxication in rats induced by intraperitoneal administration of an acetone-killed 3-day culture of the bacterial mass of the melioidosis causative agent. When prodigiozan was administered 48 hours by the 4th day which was indicative of prodigiozan activation of the factors of the microbial non-specific resistance.     

Effect of salts on the activity of carrot phosphofructokinase

Phosphofructokinase (EC 2.7.1.11) from carrot roots was activated by a number of salts. Increase in salt concentration beyond the optimum generally led to a decrease in enzyme activity. Salts of the multivalent anions sulfate and phosphate were very effective activators and inhibitors. Potassium acetate and potassium succinate were also activators. Potassium tartrate and potassium citrate produced a small stimulation at low concentration but with further increase they became inhibitory. The results suggested that the salt effect was largely due to anions rather than cations. Salts such as NaCl, KCl, and in particular potassium phosphate, relieved the inhibition of carrot phosphofructokinase by phosphoenolpyruvate. KCl and potassium phosphate also reversed the inhibition of carrot phosphofructokinase by citrate. The possible significance of these observations in the regulation of glycolysis and carbohydrate metabolism, and in salt respiration is discussed.     

Effect of temperature, salts, pH, and other factors on the development of peritrichous flagella in Vibrio alginolyticus.

The development of peritrichous flagella and, consequently, swarming of Vibrio alginolyticus depend on a complex relationship between temperature, salt concentrations and pH. At temperatures above 28 degrees C V. alginolyticus did not develop peritrichous flagella unless certain minimal concentrations of NaCl are present: the higher the temperature, the higher the NaCl concentrations required for peritrichous flagella synthesis. This requirement for NaCl at high temperatures is much more pronounced at pH 9 than at pH 6. High temperatures and low concentrations of NaCl also inhibited swarming of cells already armed with peritrichous flagella. Other cations, such as Li+, K+ and Mg2+. replaced NaCl only at temperatures below 28 degrees C.     

Effect of free and conjugated bile salts on alpha-amylase activity.

The effect of individual bile salts on alpha-amylase hydrolysis of Cibachron Blue starch was studied at pH 6.0. With sodium cholate, taurocholate and taurodeoxycholate, enzyme activity was increased to 150-160 percent of the control value, at a concentration of similar to 1 mmol/l bile salt. The increased activity extended up to 4 mmol/l. The bile salts sodium deoxycholate and taurochenodeoxycholate exerted activation and inhibition depending on the concentration. With deoxycholate (0.75 mmol/l), activation (150 percent) was evident, while inhibition was apparent above 2.5 mmol/l. With taurochenodeoxycholate maximum activity (135 percent) was observed at 0.25 mmol/l, while inhibition was evident above 1.5 mmol/l. Chenodeoxycholate and lithocholate exerted marked inhibition at concentrations as low as 0.5 mmol/l. Inhibition of alpha-amylase by chenodeoxycholate was competitive with both soluble and insoluble starch substrates. Since the pH of the jejunum is in the region of 6.0 the phenomenon of activation and inhibition of alpha-amylase by bile salts at this pH could be of physiological significance.     

Effect of cisplatin and other biological response modifiers on the activity of lysozyme, plasminogen activator and 5' nucleotidase by murine macrophages in vitro

In vitro effect of cisplatin and other biological response modifiers has been studied. It is observed that in vitro treatment of macrophage monolayers with cisplatin, rIFN Y, LPS or MDP either alone or in combination showed significantly increased activity of lysozyme, plasminogen activator and decreased activity of 5' nucleotidase. Priming of macrophages with rIFN Y had a significant effect in enhancing the activity of lysozyme and plasminogen activator when subsequently treated with cisplatin, MDP or LPS.     

Effect of lysozyme on mycobacteria

The effect of lysozyme on the growth of several strains of mycobacteria was examined at pH 5.0-7.0 in Dubos medium containing various concentrations of lysozyme (100-2,000 microgram/ml). Mycobacterium smegmatis and M. phlei were susceptible to lysozyme at pH 5.0-7.0. The effect of lysozyme was marked between pH 6.0 and 7.0 and the colony counts were reduced to approximately 0.1-10% after incubation with 100 micrograms of lysozyme per ml for 48 hr. At pH 5.0, 10-40% of the organisms survived treatment with 1,000 micrograms of lysozyme per ml for 48 hr. M. bovis strain BCG, M. tuberculosis, and M. fortuitum appeared to be more resistant to lysozyme than M. smegmatis and M. phlei. M. smegmatis and M. phlei did not contain detectable amounts of poly-L-glutamic acid, although the susceptibility of the mycobacteria to lysozyme did not correlate with the amounts of the polymer in the cell walls. The role of lysozyme in animal infections with so-called saprophytic mycobacteria is discussed.     

Effect of salts on the lytic activity of gramicidin S and its derivatives

Potassium and sodium chlorides, sulfates, acetates and phosphates activated the lytic action of gramicidin S and its derivatives on protoplasts of M. lysodeikticus. The derivatives used were positively charged and neutral by the free amino groups in the ornithine moieties. The salts had no effect on lysis of the bacillar protoplasts by gramicidin S and its positively charged derivatives. The lytic effect of the neutral derivative on the bacillar protoplasts markedly increased in the presence of the salts, activation of the lysis by the phosphates being more pronounced than that by the other salts. Increased membrane activity of gramicidin S in the presence of the salts was not connected with association of the substance molecules in solution. Probably it was due to increased destruction of the membranes at the account of activated detergent effect of the antibiotic and its derivatives.     

Effect of salts and organic solvents on the activity of Halobacterium cutirubrum catalase

Catalase in extracts of the extreme halophile Halobacterium cutirubrum exhibits up to threefold stimulation by 0.5 to 1.5 m monovalent salts and by 0.1 m divalent salts. Above these concentrations, inhibition of enzyme activity is observed. The inhibitory effect, and to some extent the stimulation, is salt-specific; the effectiveness of a salt in inhibiting enzyme activity depends on both cation and anion. Thus, the order of effectiveness is MgCl(2) > LiCl > NaCl > KCl > NH(4)Cl, and LiCl > LiNO(3) > Li(2)SO(4). The magnitude of enzyme inhibition for the salts tested is positively correlated with their molar vapor pressure depression in aqueous solution. Stimulation of enzyme activity was observed when one salt was added at its optimal concentration in the presence of inhibiting concentrations of another salt, indicating that the effect on the enzyme is not due to changing water activity but probably to enzyme-salt interaction. Aqueous solutions of ethylene glycol, glycerol, and dimethyl sulfoxide containing no ions influence enzyme activity in the same manner as do salts.     

Effect of lysozyme on the growth of murine lymphoma and antineoplastic activity of cyclophosphamide]

It was shown that hen egg-white lysozyme (LM) in the dose 100 mg/kg under the daily intragastral use slightly inhibited tumor grown or did not influence significantly upon it and did not change antitumor activity of cyclophosphamide. When used at mice C57Bl/6J with the transplanted ascitic or solid T-cell lymphoma EL4 (syngeneic system). On model of the same tumors in ascitic form at mice-hybrids (C57Bl/6J x DBA2)F1 (semisingeneic system) LM significantly potentiates antitumor activity of cyclophosphamide, though it had no effect on the rate of tumor growth. Potentiation of the effect of cyclophosphamide revealed itself in more slow development of ascite, increased mean life-span and the overall survival, appearance of completely cured animals. Our clinic-laboratory studies have revealed a sharp deficit of endogenic lysozyme in the blood serum of leukemic patients and extremely low lysozyme content in lavage liquid, from leukemic patients, with pneumonia. These data suggest that LM can be useful as a food additive in the complex treatment of oncological patients for enhancing antineoplastic chemotherapy efficacy.     

Effect of polyols on the conformational stability and biological activity of a model protein lysozyme

The purpose of this study was to investigate the stabilizing action of polyols against various protein degradation mechanisms (eg, aggregation, deamidation, oxidation), using a model protein lysozyme. Differential scanning calorimeter (DSC) was used to measure the thermodynamic parameters, mid point transition temperature and calorimetric enthalpy, in order to evaluate conformational stability. Enzyme activity assay was used to corroborate the DSC results. Mannitol, sucrose, lactose, glycerol, and propylene glycol were used as polyols to stabilize lysozyme against aggregation, deamidation, and oxidation. Mannitol was found to stabilize lysozyme against aggregation, sucrose against deamidation both at neutral pH and at acidic pH, and lactose against oxidation. Stabilizers that provided greater conformational stability of lysozyme against various degradation mechanisms also protected specific enzyme activity to a greater extent. It was concluded that DSC and bioassay could be valuable tools for screening stabilizers in protein formulations.