Electrochemical and Spectrophotometric Study of the Reactions of L-Leucine with Pyridoxal and Pyridoxal Phosphate

1994 ◽  
Vol 59 (4) ◽  
pp. 768-781
Author(s):  
T. Pineda ◽  
M. Blázquez ◽  
M. Domínguez ◽  
F. Garcia-Blanco
Keyword(s):  
Amino Acid ◽  
Schiff Bases ◽  
Formation Constant ◽  
Pyridoxal Phosphate ◽  
Mercury Electrode ◽  
Quantitative Description ◽  
Spectrophotometric Study ◽  
Acid Base ◽  
Absorption Bands ◽  
Reduction Mechanisms

The reactions of L-leucine (Leu) with pyridoxal (PL) and pyridoxal-5'-phosphate (PLP) were studied over pH 6 - 13.5. Formation of the Schiff bases was indicated by UV-VIS absorption bands and reduction waves on a mercury electrode. A comparative electrochemical and spectrophotometric study on the reaction mixtures as a function of pH and the amino acid-to-aldehyde concentration ratio was carried out. Apparent formation constant, KpH and acid-base constants for the Schiff bases were obtained. Reduction mechanisms of the imines are proposed in different pH zones. The formation constant, KSo, of an unprotonated Schiff base from unprotonated species of aldehyde and amino acid was determined by voltammetry. The results are compared to those obtained in analog Schiff bases in order to improve the quantitative description of the enzymatic models.

Spectrophotometric study of the acid-base and optical properties of the 5-bromo and 5-chloro derivatives of 2-(2-pyridylazo)-5-(diethylamino)phenol (BrPADAP, ClPADAP) and their complexation equilibria with zinc(II) ions

1982 ◽  
Vol 47 (10) ◽  
pp. 2676-2691 ◽  
Author(s):  
Miroslav Macka ◽  
Vlastimil Kubáň
Keyword(s):  
Equilibrium Constants ◽  
Spectrophotometric Study ◽  
Graphical Analysis ◽  
Alkaline Media ◽  
Acid Base ◽  
Ethanol Medium ◽  
Triton X ◽  
Mixed Water ◽  
Derivatives Of

The optical and acid-base characteristics of BrPADAP and ClPADAP were studied in mixed water-ethanol and water-DMF media and in 10% ethanol medium in the presence of cationic, anionic and nonionic tensides. The composition, optical characteristics, molar absorption coefficients and equilibrium constants of the ML and ML2 complexes with zinc(II) ions were found by graphical analysis and numerical interpretation of the absorbance curves by the modified SQUAD-G program. Optimal conditions were found for the spectrophotometric determination of Zn(II) in the presence of 0.1% Triton X-100 or 1% Brij 35 in alkaline media with pH = 6.5-10. BrPADAP and ClPADAP are the most sensitive reagents (ε = 1.3-1.6 . 105 mmol-1 cm2 at 557 and 560 nm, respectively) for the determination of zinc with high colour contrast of the reaction (Δλ = 104 nm) and selectivity similar to that for the other N-heterocyclic azodyes (PAN, PAR, etc.).

Spectrophotometric study of the interaction of Chromazurol S and Eriochromazurol B with surface active substances - tensides

1981 ◽  
Vol 46 (5) ◽  
pp. 1090-1106 ◽  
Author(s):  
Irena Burešová ◽  
Vlastimil Kubáň ◽  
Lumír Sommer
Keyword(s):  
Critical Micellar Concentration ◽  
Spectrophotometric Study ◽  
Conditional Stability ◽  
Acid Base ◽  
Binary Complexes ◽  
Chromazurol S ◽  
Acid Base Equilibrium ◽  
Poorly Soluble ◽  
Conditional Stability Constants ◽  
Triton X

The acid-base and optical properties of Chromazurol S and Eriochromazurol B in the presence of 1 . 10-6 - 2 . 10-2M solutions of cetylpyridinium bromide, cetyltrimethylammonium bromide and 1-ethoxycarbonylpentadecyltrimethylammonium bromide (Septonex) and 0.001-1.0% w/v solutions of octylphenolpolyethylene glycol ether (Triton X-100), polyoxyethylenemonolauryl ether (Brij 35) and lauryl sulphate sodium salt were determined by graphical and numerical interpretation of absorbance curves. The poorly soluble ion associates, which can be extracted into chloroform and which have the defined composition [LH4-nn-.n T+] or [LH3-nn-.n T+] are formed at submicellar concentration of the tenside. In regions close to the critical micellar concentration of the tenside, soluble binary complexes of the acid-base forms of the reagent are formed with tenside micelles. The conditional stability constants of the reagent acid-base equilibrium depend on the type and concentration of the tenside, on the reagent concentration, on the concentration and type of inorganic acid anions and on the ionic strength of the solution. The mechanism of interaction of the reagent with the tenside and the probable structure of the binary species are discussed.

Polarographic and spectrophotometric behaviour of some N-p-phenyl substituted benzamidines

1991 ◽  
Vol 56 (12) ◽  
pp. 2791-2799 ◽  
Author(s):  
Juan A. Squella ◽  
Luis J. Nuñez-Vergara ◽  
Hernan Rodríguez ◽  
Amelia Márquez ◽  
Jose M. Rodríguez-Mellado ◽  
...  
Keyword(s):  
Spectrophotometric Study ◽  
Absorption Bands ◽  
Electrochemical Parameters ◽  
Wide Ph Range ◽  
Group A ◽  
Substituent Constants ◽  
Ph Range ◽  
The Waves

Five N-p-phenyl substituted benzamidines were studied by DC and DP polarography in a wide pH range. Coulometric results show that the overall processes are four-electron reductions. Logarithmic analysis of the waves indicate that the process are irreversible. The influence of the pH on the polarographic parameters was also studied. A UV spectrophotometric study was performed in the pH range 2-13. In basic media some variations in the absorption bands were observed due to the dissociation of the amidine group. A determination of the pK values was made by deconvolution of the spectra. Correlations of both the electrochemical parameters and spectrophotometric pK values with the Hammett substituent constants were obtained.

Platinum(II) complexes of reduced amino acid ester Schiff bases: synthesis, characterization, and antitumor activity

2012 ◽  
Vol 40 (1) ◽  
pp. 413-424 ◽  
Author(s):  
Li-Jun Li ◽  
Cheng Wang ◽  
Yu Qiao ◽  
Xiao-Yan Yang ◽  
Xing-Xing Hua ◽  
...  
Keyword(s):  
Amino Acid ◽  
Antitumor Activity ◽  
Schiff Bases ◽  
Acid Ester ◽  
Amino Acid Ester

Acid-base titrations of schiff bases in deuteriomethanol as studied by1H NMR

1989 ◽  
Vol 18 (7) ◽  
pp. 691-703 ◽  
Author(s):  
M. M�kel� ◽  
O. Hormi ◽  
E. Jula ◽  
T. Korpela
Keyword(s):  
Schiff Bases ◽  
Acid Base

scholarly journals THE EFFECT OF dl-METHIONINE, l-CYSTINE, AND dl-ISOLEUCINE ON THE UTILIZATION OF PARENTERALLY ADMINISTERED DOG HEMOGLOBIN

1947 ◽  
Vol 85 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Leon L. Miller ◽  
Eric L. Alling
Keyword(s):  
Amino Acid ◽  
Developmental Stages ◽  
Peripheral Circulation ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Absorption Bands ◽  
Suggested Approach ◽  
Dog Plasma ◽  
Veronal Buffer ◽  
Definition Of

1. Further observations on the utilization of parenterally administered dog hemoglobin show that oral supplements of dl-methionine and l-cystine improve the efficiency of utilization of hemoglobin N, while a fed supplement of dl-isoleucine alone is without effect. 2. When N-isoleucine is added to a fed supplement of methionine or methionine and cystine, the utilization of parenterally given hemoglobin N is even better than with the sulfur-containing amino acids alone. 3. A suggested approach to the problem of designing the quantitatively "ideal" amino acid mixture lies in the definition of what may be called total organism-amino acid patterns of rat, dog, man, etc. These may vary considerably not only at different developmental stages in a given species, but also certainly from one species to another. 4. Further attempts to detect globin in the peripheral circulation have pointed to the need for a highly specific procedure such as that an immunologic method may offer. 5. Reduced hemin in dog plasma migrates with α1-globulin and albumin in veronal buffer at pH 8.5 and the colored zones give strong hemochromogen absorption bands.

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