Data-Table

The following PDF-file provides a data table showing the most important properties of all ATTO-Labels.  

Data-Table  (2020/03/23)

All spectral data given in this table have been measured at 22 °C on aqueous solutions (PBS, pH 7.4) of the dyes with free carboxy group. When there was a tendency to aggregate, the solution was diluted sufficiently to exhibit the monomeric absorption spectrum undisturbed by dimers. Although water is the most important solvent in biochemistry, it should be borne in mind that optical data of dyes, in particular and most pronounced the fluorescence efficiency and decay time, depend on the solvent, as well as on other environmental factors. With most ATTO-dyes this influence is very weak indeed. Furthermore optical properties depend on the derivative (carboxy, NHS-ester, etc.). For instance, fluorescence quantum yield and decay time of the maleimide may be reduced compared to the dye with carboxy group (COOH). However, this is of no avail: As soon as the dye is coupled to a substrate (protein), the fluorescence is restituted.

The table shows the molecular mass (MW) for the most frequently used derivatives the NHS-ester and maleimide used for coupling amino- and thiolgroups. The given values for MW include counterions. To aid in the analysis of biomolecule-dye conjugates, the increase in mass (Δm) and charge (Δq) that occur on coupling with an ATTO-dye. Because biomolecules as well as ATTO-dyes may carry basic (-NH₂) and acidic (-COOH, -SO₃H) substituents, both mass and electrical charge depend on pH. The data shown in the table are based on the assumption of non-protonated amino groups (-NH₂), deprotonated acid groups (-COO^-, -SO₃^-) and neutral thiol groups. This reflects the situation given in a close-to-neutral environment (pH 6 – 8). It is worth mentioning that under more acidic conditions (pH < 4) the additional, non-reactive, carboxylic acid group of dyes like ATTO 565 and ATTO 590 will be protonated. As a consequence both mass and charge will be higher by one unit than the values given in the table, which are valid for pH 6 – 8.

The values for the correction factors CF are needed to determine the degree of labeling (DOL) for biomolecules e.g. antibodies. They compensate for the absorption of a dye in a dye-conjugate at a specific wavelength. In case of protein labeling the CF₂₈₀ has to be used, for oligonucleotide labeling CF₂₆₀ is appropriate.