In spectroscopy, a Soret peak or Soret band is an intense peak in the blue wavelength region of the visible spectrum. The peak is named after its discoverer, Jacques-Louis Soret.
Examples
The Soret band arises primarily due to an electron dipole movement that allows π-π* transitions; most common in
porphyrin compounds.
Most analytical studies of porphyrincontaining moiety can be done using ultraviolet–visible spectroscopy and exciting wavelength at the respective Soret band wavelength. For example, the "Soret peak" is used to describe the absorption of vividly-pigmented
heme-containing moieties, such as various
cytochromes. For example, the
P450, a diverse class of
monooxygenase , exhibit a Soret peak at 450 nm in their reduced form when saturated with
carbon monoxide.
This is called a CO difference spectrum assay: the absorbance spectrum of the solution is subtracted from the spectrum after saturation with
carbon monoxide. If the P450 has been denatured, for example due to bad handling, the peak shifts to 420 nm. It is possible to see both 420 nm and 450 nm peaks on the same spectrum if only a portion of the P450 has been denatured.
