Protoporphyrin coefficient

Protoporphyrin fluorescence marker (no longer available, must be replaced by protoporphyrin substance, standardized by molar extinction coefficients see section 7.3.3.6, subheading Calibration ). 

Chromophores free in solution and bound to macromolecules do not display identical s values and absorption peaks. For example, free hemin absorbs at 390 nm. However, in the cytochrome b2 core extracted from the yeast Hansenula anomala, the absorption maximum of heme is located at 412 nm with a molar extinction coefficient equal to 120 mM-1 cm-1 (Albani 1985). In the same way, protoporphyrin IX dissolved in 0.1 N NaOH absorbs at 510 nm, whereas when it is bound to apohemoglobin, it absorbs in the Soret band at around 400 nm. 

The simple haem mesoporphyrin IX iron(III) methoxide has a relatively weak near infra-red band at 13.1 kK (101). The region 8—10 kK can then be studied in more detail. This compound is essentially high-spin (8, 87, 101) and the crystal structure is known in detail (8). The polarized crystal spectrum in the region 5—12 kK has been measured (96) and all the bands are in-plane polarized. Peaks are seen at 11.4, 9.3, 8.3 and 7.2 kK, with a shoulder at 10.2 kK. The bands are so evenly spaced as to suggest a vibrational progression, and the interval of about 1.1 kK is about the same as the usually a—/J separation in typical metalloporphy-rin spectra. This absorption could be due to the low-spin form the extinction coefficients are around 50, and protoporphyrin IX iron(III) methoxide, which has a very similar visible spectrum (101), has a magnetic moment (8) which suggests the presence of some 20% of the low-spin form. 

This esterified hemin is soluble in ligating solvents such as pyridine and also halogenated hydrocarbons, ethers such as tetrahydrofuran, and benzene. It is slightly soluble in alcohols and insoluble in water. In the presence of traces of water in a solution it will slowly convert to the n-oxo form. It can also dehydrate to the proto forms i under specific conditions. Other chemical, physical, and biological properties are similar to those for the protoporphyrin IX com-plex.i Extinction coefficients for the various characteristic spectra of this material are not well defined, as the solutions are generally unstable with time, going to mixtures of the various ligated and jx-oxo forms. 

LA Control group. The results of the control group for Pb in blood and in 24 hours urine are shown in Table I. In Table 2 are presented the values of ALA-D and protoporphyrin IX in erythrocytes for the same population and in Table III those of the hemoglobin concentration and protoporphirin IX/g of haemoglobin coefficient. In table 4 are indicated the values of 5-ALA and porphobilinogen (PEG) in 24 hours urine and in the last (table 5) are presented the results found in urine of 24h of uroporphyrins and coproporphyrins. 

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