Molar absorbance spectrum

The spectral overlap / is obtained from the overlap, on a wavenumber or wavelength scale, of the absortion spectrum of A, where intensity is in molar absorbance, with an area-normalized emission spectrum of D. I has units of M 1cm3... 

Reaction of the apoenzyme with various metal ions allows the preparation of other metallocarbonic anhydrases and the Cu(II), Co(II) and Co(III) enzymes have been prepared. The cobalt(II) enzyme shows some catalytic activity. The d-d spectrum of the cobalt(II) derivative, which is high spin, is markedly pH dependent (Fig. 5-19). A plot of the molar absorbance at 640 nm versus pH does not follow a simple pattern, as expected for a single ionising group, but is consistent with two ionising groups with pK values of < 6 and > 7. 

All anions which bind to the Cu(II) in galactose oxidase lower the gzz and Azz values (22). This is consistent with (but not required for) a blue shift in the d-d transitions (32, 33, 34). Fe(CN)63" is the only anion among the limited ones we have studied which produces a red shift in the optical bands (Figure 4). At 1 1, 5 1, or 100 1 molar ratios of Fe(CN)63" to enzyme the same difference absorbance spectrum is obtained, and it is consistent with complex formation between galactose oxidase and the anion. Namely, the positive difference peaks at 455, 830,... 

Fe(CN)64" also apparently binds to the protein the difference absorbance spectrum (Figure 4) indicates a small red shift. Again, increasing the molar ratio of ferrocyanide causes no further absorbance changes. The two anions added at identical 5 1 molar ratios to enzyme cause a difference spectrum consistent with a competitive binding to the protein the resultant difference absorbance is that expected for an equal partitioning of the enzyme between the two anions (Figure 4). 

A typical spectrum is shown in Figure 10. The intensity of a band is measured by the molar absorbance (or extinction... 

The UV spectra of tadalafil (5 gg/mL) in aqueous solutions with various pH values were recorded with 10-mm quartz cell using a Hitachi U2010 spectrophotometer (Tokyo, Japan). The aqueous solutions used were 0.1 N HCl (pH 1.2) and 50 mM phosphate buffers (pH 4.5, 6.8, and 9.2). Tadalafil exhibited similar absorption spectrum in acidic, neutral, and basic medium, with high molar absorbance around 220, 280, and 290 nm [33]. 

The extent of substitution is determined from the ultraviolet (UV) absorbance spectrum and the protein concentration. The latter is determined by a standard chemical assay. The protein contribution to the of the conjugate is determined from the known spectrum of unmodified protein for the measured concentration. The difference between the total A260 of the conjugate and the A260 due to protein is contributed by the nucleoside. The molar concentration of nucleoside is calculated from this difference, using published extinction coefficients. ... 

The current best resolved absorption spectrum of the ascorbate anion radical (Figure 1) was determined (26) in a study of ascorbate oxidation by halide anion radicals (particularly Br2") at pH 11. The spectrum shows a symmetrical Gaussian-type band with an absorption peak at 360 nm and a width at half-maximum of about 50 nm. The molar absorbance at 360 nm = 3300 M cm" is lower than earlier reported values 21,23). 

Crystals from water + acetone, mp 196-200". [alff -47,5 (c = 2, 2% NaOH) -26.0 (c = 2, 10% HCI). pK, -- 3.8 pKj — 6.2. aM (molar absorbancy) 15.4 X I03 at 259 nm (pH 7.0). Readily sol in boiling water. The compound is readily deaminated by nitrous acid to form inosinic acid less rapidly hydrolyzed than 3 -adenylic acid by sulfuric acid. Furfural is formed only in traces On distillation with 20% HCI, cf. Levene, Bass, Nucleic Acids (New York, 1931) pp 230-232. Absorption spectrum Kalckar. foe. cir. thERap cat-. Nutrient. 

Tetrahedral complexes of Mn11 are yellow-green, and the coior is more intense than that of the octahedral complexes. A typical spectrum is shown in Fig. 20-17. First it will be noted that the molar absorbance values are in the range 1.0-4.0, whereas for octahedral Mn" complexes (see Fig. 20-17), they are in the range 0.01-0.04. This increase by a factor of about 100 in the intensities of tetrahedral complexes over octahedral ones is entirely typical. The reasons for it are not known with complete certainty, but it is... 

The absorbance spectrum A(X) is linearly related to the absorption pathlength L, the wavelength-dependent molar absorption coefficient e X), and the concentration of an analyte c ... 

Spectrophotometric examination of isolated pigments is extremely valuable in determining the purity of a carotenoid. The absorption spectrum of a carotenoid is a function of its structure and, if pure, there is good band resolution. Comparison of the absorbance spectrum to that of an authentic sample in the same solvent or to the speqtrum reported in the literature, indicates the identity and purity of a carotenoid. Further evidence of purity is obtained from molar extinction coefficients. 

Interestingly, the first oxidation potential of 4, 10 and 22 occurs around 1.55 V vs. NHE, and involves the simultaneous one-electron oxidation of all the equivalent peripheral metal centers. Figure 3 shows the different overlap of 4 and [Ru(bpy)3] " with the solar spectrum at the sea level beside the higher molar absorbance at all wavelengths, 4 covers much better the red... 

This complex was found to constitute 20 % of the hydrolysis mixture and can be eluted from the column with 0.6 M sodium perchlorate solution adjusted to pH 2.0. A chromium to cyanide ratio of 1 1.00 was determined by analysis for this pink, permanganate-colored species. The visible and ultraviolet spectrum of cyanopentaaquochromium(III) ion is independent of pH in the regions from 2 to 3.5 and is included in Fig. 4. The positions of the maxima (in mp) and corresponding molar absorbancy indices (in / mole cm ) in 0.6M sodium perchlorate are 525 (26.0), and 393 (20.5). The strong absorption band in the ultraviolet shows a point of inflection a = 268 I mole" cm" ) at 235 mp. The positions of the absorption maxima are identical to those reported by Espenson. Dilute solutions (pH 2) of the monocyano complex can be stored at 0° for several days without serious decomposition. 

Figure 1. Variation of the PB spectrum in the presence of yCD at pH 5.70 in aqueous 1.00 mol c3m NaCl at 298.2 K. The molar absorbance at 550 nm decreases systematically as the total [yCD] increases secjuentially from 0-4.093 x io mol dm". Total [PB] = 9.7 x mol dm . These...

To this end, relationships were established between the four fractions /dift(A), /free(A),/ 2W, and/Eo(A) (/el(A) is redundant since it equals 1 -/diff(A) -/foeW -fkiW -/eoW) obtained at each excitation wavelength and the parameters / , f Q, cmW, and ceoW- Thus, these relationships yielded four independent equations that depended on six variables. The molar absorbance coefficient of the pyrene monomer in water cmW was determined by preparing a Py-PDMA sample with a very low pyrene content of 6 pmol g (Py(6)-PDMA). Py(6)-PDMA generated a minimum level of pyrene aggregation which allowed the determination of cmC ) from the absorption spectrum. Equating the absorbance of an aqueous solution of a Py-PDMA sample determined experimentally to the concentrations of pyrene species present in solution provided a fifth equation that enabled the determination of the molar fractions / e /k fm most importantly, eEo( )> the molar absorbance coefficient of a pyrene aggregate. 

Together 150 monomer fluorescence decays and 150 excimer fluorescence decays were acquired and fitted globally according to the FBM to yield six sets of fractions /diff(A), /freeW, fkiW, /eoW, and /elW for each polymer solution. The procedure described above was applied to these six sets of /eoW. and /elW values which varied with the pyrene content and polymer concentration of the Py-PDMA samples. However, the procedure accounted successfully for these variations yielding a tight set of CeoW values for a range of 2ex between 325 and 350 nm with 1 nm increments (Fig. 15). This study provided the first spectrum of the molar absorbance coefficient CeoW of pyrene aggregates in water. The Pa value obtained from the e X) spectrum equaled 1.5 0.1, much lower than the Pa value of 2.5 found for the isolated pyrene monomers of Py(6)-PDMA. 

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