scholarly journals SPECTROSCOPY OF CATALASE

1937 ◽  
Vol 20 (4) ◽  
pp. 631-648 ◽  
Author(s):  
Kurt G. Stern
Keyword(s):  
Carbon Monoxide ◽  
Ferric Iron ◽  
Reducing Agents ◽  
Ultraviolet Region ◽  
Absorption Bands ◽  
Main Absorption Band ◽  
Nitrogen Bases ◽  
Nitrogenous Substances ◽  
The Stability ◽  
Blood Pigment

Catalase is resistant to oxidizing agents; e.g., ferricyanide. It is also resistant to reducing agents; e.g., catalytically activated hydrogen, hydrosulfite, ferrotartrate, cysteine. The hemin group of the enzyme will combine with cyanide, sulfides, nitric oxide, fluoride. It will not combine with carbon monoxide. Catalase is therefore a ferric complex. The stability of the ferric iron in the enzyme toward reducing agents is not due to the structure of the porphyrin with which it is combined. This porphyrin is the protoporphyrin of the blood pigment. In combination with globin (methemoglobin) the ferric iron is readily reduced by the same reagents which have no effect on catalase. The stability of the ferric iron in the enzyme is therefore due to the protein component. It may be that the type of hematin-protein linkage in catalase is the reason for this phenomenon. The suggestion of Bersin (31), that sulfur may participate in this linkage, is interesting but, as yet, has no experimental basis. Hydrazine or pyridine and hydrosulfite convert catalase into hemochromogens containing ferrous iron. But in these hemochromogens the hematin is no longer attached to the protein. This has been replaced by the nitrogenous bases hydrazine and pyridine. Both hemochromogens combine reversibly with carbon monoxide. Photo-dissociation has only been demonstrated in the case of the pyridine hemochromogen. The positions of the absorption bands of catalase and its derivatives are listed in Table II. The main absorption band (Soret's band) of hemin complexes with nitrogenous substances (nitrogen bases, proteins) is situated at the border between the visible and the ultraviolet region of the spectrum. It has now been found that the spectrum of purified liver catalase has a well defined maximum of high extinction in this range, at 409 mµ. This is further evidence for the hemin nature of the enzyme.

Rotational analysis of the forbidden d3 Δi ← X1Σ+ absorption bands of carbon monoxide

1970 ◽  
Vol 48 (24) ◽  
pp. 3004-3015 ◽  
Author(s):  
G. Herzberg ◽  
T. J. Hugo ◽  
S. G. Tilford ◽  
J. D. Simmons
Keyword(s):  
Carbon Monoxide ◽  
High Resolution ◽  
Intensity Distribution ◽  
Vacuum Ultraviolet ◽  
Ultraviolet Region ◽  
Rotational Analysis ◽  
Absorption Bands ◽  
Local Perturbations ◽  
Vacuum Ultraviolet Region ◽  
Π State

The forbidden d3Δi–X1Σ+ transition of CO has been observed in absorption at high resolution in the vacuum ultraviolet region. The intensity distribution in the rotational structure of the observed bands is in conformity with the assumption that the transition occurs on account of the interaction between the d3Δ state and a 1Π state, presumably the A1Π state. Thirteen bands of the d–X system have been analyzed yielding more extensive rotational data for the d3Δi state than were previously known. A discussion of the local perturbations in the d state by the A1Π and a3Π states is included.

THE FORBIDDEN I1Σ−–X1Σ+ ABSORPTION BANDS OF CARBON MONOXIDE

1966 ◽  
Vol 44 (12) ◽  
pp. 3039-3045 ◽  
Author(s):  
G. Herzberg ◽  
J. D. Simmons ◽  
A. M. Bass ◽  
S. G. Tilford
Keyword(s):  
Carbon Monoxide ◽  
Selection Rule ◽  
Vacuum Ultraviolet ◽  
Ultraviolet Region ◽  
Absorption Bands ◽  
Coriolis Interaction ◽  
Dipole Radiation ◽  
Vacuum Ultraviolet Region ◽  
Vibrational Constants ◽  
Π State

The forbidden I1Σ−–X1Σ+ transition of CO has been observed in absorption at high resolution in the vacuum ultraviolet region. As expected for a 1Σ−–1Σ+ transition, the bands consist of single Q branches, in which the lines of lowest J are either missing or very weak. Although the selection rule prohibiting Σ−–Σ+ transitions is rigorous for dipole radiation at zero rotation, the I1Σ−–X1Σ+ transition can occur for higher rotational levels because of Coriolis interaction with the A1Π state, which lies very close to the I1Σ− state.Eight bands of the I–X system have been analyzed and from them the rotational and vibrational constants of the I1Σ− state have been determined. Previous information on this state was based entirely on the study of perturbations in the A1Π state. The corresponding perturbations in the I1Σ− state have now been observed. In addition, small "vibrational" perturbations in the ν = 4 and 5 levels (probably caused by interactions with the a3Π state) are found.

Methods for the Concentration of Bovine Ac-Globulin (Factor V)

1961 ◽  
Vol 06 (03) ◽  
pp. 435-444 ◽  
Author(s):  
Ricardo H. Landaburu ◽  
Walter H. Seegers
Keyword(s):  
Room Temperature ◽  
Barium Carbonate ◽  
Deae Cellulose ◽  
Reducing Agents ◽  
Factor V ◽  
Isoelectric Precipitation ◽  
Stabilizing Agent ◽  
Bovine Plasma ◽  
The Stability

SummaryAn attempt was made to obtain Ac-globulin from bovine plasma. The concentrates contain mostly protein, and phosphorus is also present. The stability characteristics vary from one preparation to another, but in general there was no loss before 1 month in a deep freeze or before 1 week in an icebox, or before 5 hours at room temperature. Reducing agents destroy the activity rapidly. S-acetylmercaptosuccinic anhydride is an effective stabilizing agent. Greatest stability was at pH 6.0.In the purification bovine plasma is adsorbed with barium carbonate and diluted 6-fold with water. Protein is removed at pH 6.0 and the Ac-globulin is precipitated at pH 5.0. Rivanol and alcohol fractionation is followed by chromatography on Amberlite IRC-50 or DEAE-cellulose. The final product is obtained by isoelectric precipitation.

Natural Vulcanization Accelerators in Hevea Latex

1948 ◽  
Vol 21 (4) ◽  
pp. 853-859
Author(s):  
R. F. A. Altman
Keyword(s):  
Amino Acids ◽  
Experimental Results ◽  
The Other ◽  
Active Nitrogen ◽  
Nitrogen Bases ◽  
Other Hand ◽  
Decomposition Processes ◽  
Volatile Products ◽  
Nitrogenous Substances ◽  
The One

Abstract As numerous investigators have shown, some of the nonrubber components of Hevea latex have a decided accelerating action on the process of vulcanization. A survey of the literature on this subject points to the validity of certain general facts. 1. Among the nonrubber components of latex which have been investigated, certain nitrogenous bases appear to be most important for accelerating the rate of vulcanization. 2. These nitrogen bases apparently occur partly naturally in fresh latex, and partly as the result of putrefaction, heating, and other decomposition processes. 3. The nitrogen bases naturally present in fresh latex at later stages have been identified by Altman to be trigonelline, stachhydrine, betonicine, choline, methylamine, trimethylamine, and ammonia. These bases are markedly active in vulcanization, as will be seen in the section on experimental results. 4. The nitrogenous substances formed by the decomposition processes have only partly been identified, on the one hand as tetra- and pentamethylene diamine and some amino acids, on the other hand as alkaloids, proline, diamino acids, etc. 5. It has been generally accepted that these nitrogenous substances are derived from the proteins of the latex. 6. Decomposition appears to be connected with the formation of a considerable amount of acids. 7. The production of volatile nitrogen bases as a rule accompanies the decomposition processes. These volatile products have not been identified. 8. The active nitrogen bases, either already formed or derived from complex nitrogenous substances, seem to be soluble in water but only slightly soluble in acetone.

Effect of the ionizing radiation on the catalytic activity of the BASF K-3-10 catalyst in the low-temperature conversion of carbon monoxide by water vapour. Stability of the radiation catalytic effects

1986 ◽  
Vol 51 (8) ◽  
pp. 1571-1578 ◽  
Author(s):  
Alois Motl
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Low Temperature ◽  
Catalytic Effect ◽  
Catalytic Properties ◽  
Beta Radiation ◽  
Fast Neutrons ◽  
Time Interval ◽  
The Stability ◽  
Catalytic Effects

The radiation catalytic properties of the BASF K-3-10 catalyst were studied, namely the dependence of these effects on the time interval between the catalyst irradiation and the reaction itself and also on the length of the catalyst use. The catalytic effects decrease exponentially with the interval between the irradiation and the reaction if the catalyst is kept in the presence of air. The stability of effects induced by various types of radiations increases in the sequence beta radiation - gamma radiation - fast neutrons. The radiation catalytic effect stability in the reaction increases in the same sequence.

Stability of carbon monoxide oxidation process on gold nanoparticles

2020 ◽  
Vol 8 (1) ◽  
pp. 116-124
Author(s):  
P. P. Kostrobij ◽  
◽  
I. A. Ryzha ◽  
Keyword(s):  
Carbon Monoxide ◽  
Gold Nanoparticles ◽  
Reaction Mechanisms ◽  
Structural Changes ◽  
Oxidation Process ◽  
Lyapunov Method ◽  
Catalyst Surface ◽  
Carbon Monoxide Oxidation ◽  
One Step ◽  
The Stability

The stability conditions for mathematical models of carbon monoxide oxidation on the surface of gold nanoparticles are investigated. The cases of reaction mechanisms of one-step and step-by-step transformation of reagents are consecutively considered. Using the stability analysis by Lyapunov method, it is shown that models which take into account the possibility of structural changes of the catalyst surface can predict the occurrence of oscillatory mode in the system as a result of Hopf instability.

Intrinsic Defects in GaAs - the Case of El2

1987 ◽  
Vol 104 ◽  
Author(s):  
H. J. Von Bardeleben ◽  
D. Stievemard
Keyword(s):  
Electronic Structure ◽  
Stable Configuration ◽  
Theoretical Studies ◽  
Absorption Bands ◽  
Teller Distortion ◽  
Jahn Teller ◽  
The Stability ◽  
Additional Support ◽  
Jahn Teller Distortion ◽  
Experimental And Theoretical Studies

ABSTRACTThe arsenic antisite-arsenic interstitial pair model for the stable configuration of the EL2 defect in GaAs has stimulated new experimental and theoretical studies, the results of which lead to additional support for this model. Recent theoretical studies, taking into account the effect of a Jahn Teller distortion of the T2 Asi levels have given an insight into the stability and the electronic structure of the defect pair. Further, ODENDOR studies have directly confirmed this model and allowed one to specify the lattice location and the charge state of the Asi ion. The pair structure of this defect implies a reconsideration of the charge states of the EL2 defect, as well as the origin of the optical absorption bands for which transitions on the Asi ion and intracenter bands have also to be considered. The model leads further to a description of the metastable configuration : an arsenic molecule at the gallium vacancy site, the electronic structure of which is calculated. The vacancy related defects, known from electron irradiation studies, are not detected in LEC grown GaAs as native defects.

Control of oxidation-reduction potential during Cheddar cheese ripening and its effect on the production of volatile flavour compounds

2016 ◽  
Vol 83 (4) ◽  
pp. 479-486 ◽  
Author(s):  
Veronica Caldeo ◽  
John A Hannon ◽  
Dara-Kate Hickey ◽  
Dave Waldron ◽  
Martin G Wilkinson ◽  
...  
Keyword(s):  
Redox Potential ◽  
Cheddar Cheese ◽  
Principal Component ◽  
Reducing Agents ◽  
Sulphur Compounds ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Volatile Flavour ◽  
Redox Agents ◽  
The Stability

In cheese, a negative oxidation-reduction (redox) potential is required for the stability of aroma, especially that associated with volatile sulphur compounds. To control the redox potential during ripening, redox agents were added to the salted curd of Cheddar cheese before pressing. The control cheese contained only salt, while different oxidising or reducing agents were added with the NaCl to the experimental cheeses. KIO3 (at 0·05, 0·1 and 1%, w/w) was used as the oxidising agent while cysteine (at 2%, w/w) and Na2S2O4 (at 0·05 and 0·1%, w/w) were used as reducing agents. During ripening the redox potential of the cheeses made with the reducing agents did not differ significantly from the control cheese (Eh ≈ −120 mV) while the cheeses made with 0·1 and 0·05% KIO3 had a significantly higher and positive redox potential in the first month of ripening. Cheese made with 1% KIO3 had positive values of redox potential throughout ripening but no starter lactic acid bacteria survived in this cheese; however, numbers of starter organisms in all other cheeses were similar. Principal component analysis (PCA) of the volatile compounds clearly separated the cheeses made with the reducing agents from cheeses made with the oxidising agents at 2 month of ripening. Cheeses with reducing agents were characterized by the presence of sulphur compounds whereas cheeses made with KIO3 were characterized mainly by aldehydes. At 6 month of ripening, separation by PCA was less evident. These findings support the hypothesis that redox potential could be controlled during ripening and that this parameter has an influence on the development of cheese flavour.

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