scholarly journals Mixtures of l-Amino Acids as Reaction Medium for Formation of Iron Nanoparticles: The Order of Addition into a Ferrous Salt Solution Matters

2013 ◽  
Vol 14 (10) ◽  
pp. 19452-19473 ◽  
Author(s):  
Karolína Šišková ◽  
Libor Machala ◽  
Jiři Tuček ◽  
Josef Kašlík ◽  
Peter Mojzeš ◽  
...  
Keyword(s):  
Amino Acids ◽  
Salt Solution ◽  
Iron Nanoparticles ◽  
Reaction Medium ◽  
Ferrous Salt

scholarly journals INACTIVATION AND REACTIVATION OF B. MEGATHERIUM PHAGE

1955 ◽  
Vol 39 (2) ◽  
pp. 225-249 ◽  
Author(s):  
John H. Northrop ◽  
Keyword(s):  
Amino Acids ◽  
Temperature Coefficient ◽  
Trypsin Inhibitor ◽  
Salt Solution ◽  
Effect Of Temperature ◽  
Intermediate Step ◽  
Heat Of Reaction ◽  
Reversible Inactivation ◽  
Inactivation Curve ◽  
Bean Trypsin Inhibitor

Preparation of Reversibly Inactivated (R.I.) Phage.— If B. megatherium phage (of any type, or in any stage of purification) is suspended in dilute salt solutions at pH 5–6, it is completely inactivated; i.e., it does not form plaques, or give rise to more phage when mixed with a sensitive organism (Northrop, 1954). The inactivation occurs when the phage is added to the dilute salt solution. If a suspension of the inactive phage in pH 7 peptone is titrated to pH 5 and allowed to stand, the activity gradually returns. The inactivation is therefore reversible. Properties of R.I. Phage.— The R.I. phage is adsorbed by sensitive cells at about the same rate as the active phage. It kills the cells, but no active phage is produced. The R.I. phage therefore has the properties of phage "ghosts" (Herriott, 1951) or of colicines (Gratia, 1925), or phage inactivated by ultraviolet light (Luria, 1947). The R.I. phage is sedimented in the centrifuge at the same rate as active phage. It is therefore about the same size as the active phage. The R.I. phage is most stable in pH 7, 5 per cent peptone, and may be kept in this solution for weeks at 0°C. The rate of digestion of R.I. phage by trypsin, chymotrypsin, or desoxyribonuclease is about the same as that of active phage (Northrop, 1955 a). Effect of Various Substances on the Formation of R.I. Phage.— There is an equilibrium between R.I. phage and active phage. The R.I. form is the stable one in dilute salt solution, pH 5 to 6.5 and at low temperature (<20°C.). At pH >6.5, in dilute salt solution, the R.I. phage changes to the active form. The cycle, active ⇌ inactive phage, may be repeated many times at 0°C. by changing the pH of the solution back and forth between pH 7 and pH 6. Irreversible inactivation is caused by distilled water, some heavy metals, concentrated urea or quanidine solutions, and by l-arginine. Reversible inactivation is prevented by all salts tested (except those causing irreversible inactivation, above). The concentration required to prevent R.I. is lower, the higher the valency of either the anion or cation. There are great differences, however, between salts of the same valency, so that the chemical nature as well as the valency is important. Peptone, urea, and the amino acids, tryptophan, leucine, isoleucine, methionine, asparagine, dl-cystine, valine, and phenylalanine, stabilize the system at pH 7, so that no change occurs if a mixture of R.I. and active phage is added to such solutions. The active phage remains active and the R.I. phage remains inactive. The R.I. phage in pH 7 peptone becomes active if the pH is changed to 5.0. This does not occur in solutions of urea or the amino acids which stabilize at pH 7.0. Kinetics of Reversible Inactivation.— The inactivation is too rapid, even at 0° to allow the determination of an accurate time-inactivation curve. The rate is independent of the phage concentration and is complete in a few seconds, even in very dilute suspensions containing <1 x 104 particles/ml. This result rules out any type of bimolecular reaction, or any precipitation or agglutination mechanism, since the minimum theoretical time for precipitation (or agglutination) of a suspension of particles in a concentration of only 1 x 104 per ml. would be about 300 days even though every collision were effective. Mechanism of Salt Reactivation.— Addition of varying concentrations of MgSO4 (or many other salts) to a suspension of either active or R.I. phage in 0.01 M, pH 6 acetate buffer results in the establishment of an equilibrium ratio for active/R.I. phage. The higher the concentration of salt, the larger proportion of the phage is active. The results, with MgSO4, are in quantitative agreement with the following reaction: See PDF for Equation Effect of Temperature.— The rate of inactivation is too rapid to be measured with any accuracy, even at 0°C. The rate of reactivation in pH 5 peptone, at 0 and 10°, was measured and found to have a temperature coefficient Q10 = 1.5 corresponding to a value of E (Arrhenius' constant) of 6500 cal. mole–1. This agrees very well with the temperature coefficient for the reactivation of denatured soy bean trypsin inhibitor (Kunitz, 1948). The equilibrium between R.I. and active phage is shifted toward the active side by lowering the temperature. The ratio R.I.P./AP is 4.7 at 15° and 2.8 at 2°. This corresponds to a change in free energy of –600 cal. mole–1 and a heat of reaction of 11,000. These values are much lower than the comparative one for trypsin (Anson and Mirsky, 1934 a) or soy bean trypsin inhibitor (Kunitz, 1948). Neither the inactivation nor the reactivation reactions are affected by light. The results in general indicate that there is an equilibrium between active and R.I. phage. The R.I. phage is probably an intermediate step in the formation of inactive phage. The equilibrium is shifted to the active side by lowering the temperature, adjusting the pH to 7–8 (except in the presence of high concentrations of peptone), raising the salt concentration, or increasing the valency of the ions present. The reaction may be represented by the following: See PDF for Equation The assumption that the active/R.I. phage equilibrium represents an example of native/denatured protein equilibrium predicts all the results qualitatively. Quantitatively, however, it fails to predict the relative rate of digestion of the two forms by trypsin or chymotrypsin, and also the effect of temperature on the equilibrium.

scholarly journals Synthesis, Structural, and Antimicrobial Studies of Some New Coordination Compounds of Palladium(II) with Azomethines Derived from Amino Acids

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Monika Gupta ◽  
Sangeeta Sihag ◽  
A. K. Varshney ◽  
S. Varshney
Keyword(s):  
Amino Acids ◽  
Coordination Compounds ◽  
Reaction Medium ◽  
Molar Ratio ◽  
Spectral Studies ◽  
Antimicrobial Studies ◽  
Elemental Analyses ◽  
C Nmr ◽  
Insecticidal Activities

Some new coordination compounds of palladium(II) have been synthesized by the reaction of palladium(II) acetate with azomethines in a 1 : 2 molar ratio using acetonitrile as a reaction medium. Azomethines used in these studies have been prepared by the condensation of 2-acetyl fluorene and 4-acetyl biphenyl with glycine, alanine, valine, and leucine in methanol. An attempt has been made to probe their bonding and structures on the basis of elemental analyses and IR,1H, and13C NMR spectral studies. Pd(II) compounds have been found to be more active than their uncomplexed ligands as both of them were screened for antibacterial, antifungal, and insecticidal activities.

scholarly journals Keratin Hydrolysates Extracted from Sheep Wool with Potential Use as Organic Fertilizer

2020 ◽  
Vol 20 (3) ◽  
pp. 267-276
Author(s):  
Mariana Daniela Berechet ◽  
Demetra Simion ◽  
Maria Stanca ◽  
Cosmin-Andrei Alexe ◽  
Ciprian Chelaru ◽  
...  
Keyword(s):  
Amino Acids ◽  
Particle Size ◽  
Organic Fertilizer ◽  
Control Sample ◽  
Reaction Medium ◽  
Organic Fertilizers ◽  
Particle Measurements ◽  
Potential Use ◽  
Wheat Seeds ◽  
Sheep Wool

Keratin hydrolysates were obtained from sheep wool by alkaline hydrolysis at different concentrations of KOH (3%, 5% and 8%) and temperatures (75°C, 85°C, 95°C and 99°C) of the reaction medium. The protein content of the keratin extracts was between 65.54% and 87.10%. Particle measurements showed a decrease in particle size with the increase of concentration and temperature of the reaction medium. The ATR-FTIR spectra revealed specific bands to proteins and sulfur originated from keratin amino acids. The keratin hydrolysate type KerK895 was further investigated as organic fertilizer for two types of wheat seeds. The results showed that the use of 5% KerK895 led to the increase of the wheat stems lengths by 10.7% for Mirastar wheat and 18.3% for Tamino wheat, respectively, compared to control sample. Keratin hydrolysates are promising biopolymers as organic fertilizers in agriculture applications.

scholarly journals Formation of Zero-valent Iron Nanoparticles Mediated by Amino Acids

2013 ◽  
Vol 18 ◽  
pp. 809-817 ◽  
Author(s):  
Karolina Machalova Siskova ◽  
Jana Straska ◽  
Michal Krizek ◽  
Jiri Tucek ◽  
Libor Machala ◽  
...  
Keyword(s):  
Amino Acids ◽  
Iron Nanoparticles ◽  
Zero Valent Iron ◽  
Zero Valent Iron Nanoparticles

Effect of solution's pH and molecular structure of three linear α-amino acids on the corrosion of tin in salt solution: A combined experimental and theoretical approach

2019 ◽  
Vol 1196 ◽  
pp. 105-118 ◽  
Author(s):  
Brahim El Ibrahimi ◽  
Aaziz Jmiai ◽  
Khadija El Mouaden ◽  
Ali Baddouh ◽  
Souad El Issami ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Amino Acids ◽  
Salt Solution ◽  
Theoretical Approach

scholarly journals Formation of Fe(0)-Nanoparticles via Reduction of Fe(II) Compounds by Amino Acids and Their Subsequent Oxidation to Iron Oxides

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
K. Klačanová ◽  
P. Fodran ◽  
P. Šimon ◽  
P. Rapta ◽  
R. Boča ◽  
...  
Keyword(s):  
Amino Acids ◽  
Iron Oxide ◽  
Amino Acid ◽  
Iron Oxides ◽  
Iron Oxide Nanoparticles ◽  
Coordination Compounds ◽  
Iron Nanoparticles ◽  
Reducing Agent ◽  
Oxide Nanoparticles ◽  
Optimum Ph

Iron nanoparticles were prepared by the reduction of central Fe(II) ion in the coordination compounds with amino acid ligands. The anion of the amino acid used as a ligand acted as the reducing agent. Conditions for the reduction were very mild; the temperature did not exceed 52°C, and the optimum pH was between 9.5 and 9.7. The metal iron precipitated as a mirror on the flask or as a colloid in water. Identification of the product was carried out by measuring UV/VIS spectra of the iron nanoparticles in water. The iron nanoparticles were oxidized by oxygen yielding a mixture of iron oxides. Oxidation of Fe(0) to Fe(II) took several seconds under air. The size and properties of iron oxide nanoparticles were studied by UV/VIS, TEM investigation, RTG diffractometry, Mössbauer spectroscopy, magnetometry, thermogravimetry, and GC/MS.

scholarly journals Synthesis of renin substrate by rat liver

1979 ◽  
Vol 184 (1) ◽  
pp. 7-12 ◽  
Author(s):  
A T Chiu ◽  
J W Ryan ◽  
F T Bryan ◽  
R E Niemeyer ◽  
D R Schultz
Keyword(s):  
Amino Acids ◽  
Rat Liver ◽  
Salt Solution ◽  
Molecular Sieve ◽  
Radioactive Substance ◽  
Converting Enzyme ◽  
Renin Substrate ◽  
Isolated Rat Liver ◽  
Extensive Evaluation ◽  
Isolated Rat

The present study attempts to determine if the isolated rat liver is capable of synthesizing renin substrate from 14C-labelled amino acids added in the perfusate. The renin substrate is characterized via reaction with renin, forming a substance that is subsequently identified as proangiotensin. Extensive evaluation of the reaction product is carried out by using molecular-sieve chromatography, countercurrent distribution, reactivity with converting enzyme, radioimmunological technique and bioassay. The results demonstrate that isolated rat liver perfused with artificial salt solution is capable of synthesizing a protein that reacts with renin to form a radioactive substance indistinguishable from proangiotensin.

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