Quantifying Phage Virions
Cell Origins provides researchers with critical phage-based laboratory services and kits. We focus on the use of filamentous phage as an inexpensive, reliable, highly stable, and effective replacement for many products currently on the market.
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This protocol is the routine procedure for the quantification of filamentous phage particles. The absorbance of phage DNA and protein is measured spectrophotometrically and used to calculate virions/mL (V/mL).
This protocol is based on and modified from the The Laboratory of George P. Smith at the University of Missouri. The protocols were previously hosted by http://www.biosci.missouri.edu/smithgp/
Protocol
Filamentous phages contain approximately six times more protein than DNA. Thus, the protein contributes substantially to the absorption spectrum accounting for a broad plateau at 260–280 nm with a shallow maximum at 269 nm. The calculation of the phage concentration in virions/mL (V/mL) is based on Day et al., 1978 and is as follows:
Subtracting A320, a wavelength where there is little light absorption from phage chromophores, is meant to correct crudely for light scattering from phage particles and non-phage particulate contaminants.
Example calculation of a solution of phage clones with a genome of 9312 bases:
Tips & Tricks
- For the most accurate results use a phage-free solution as a blank (background) measurement.
Related Protocols
- Library Amplification
- Amplification of Individual Phage Clones
- Large Scale Phage Purification
- Small Scale Phage Purification (Individual Clones)
- Titering Transducing Units (TU/mL)