Applied Photophysics Ltd

Fluorescence Polarisation Test Chemistry - Kinetic Measurement

Phloxine B binds quite well to bovine serum albumin and produces a good polarisation change. The optimal wavelengths when using phloxine are 535nm for excitation and 560nm for emission, however, since glass cut-off filters are used with the fluorescence polarisation accessory, 515nm has been found to be a satisfactory excitation wavelength when used with a 550nm filter.

Sample Preparation

Solution 1:-   10 -5 M bovine serum albumin in buffer
Solute: Bovine Serum Albumin (BSA)
Source: Sigma A-4378
MW: 66000
Conc: 10 -5 M

Preparation of stock solution (10 -4 M):-
Dissolve 33mg in 5mL of pH7 phosphate buffer (10mM)

Preparation of working solution (10 -5 M):-
Dilute 1mL stock solution in 10mL pH7 phosphate buffer (ie. 1:10)

Note:   The BSA stock solution is the same as is prepared for the regular flourescence test.

Solution 2:-   10 -5 M phloxine in buffer
Solute: Phloxine B (Cyanosine)
Source: Sigma P-2759
MW: 830
Conc: 10 -5 M

Preparation of stock solution (10 -2 M):-
Dissolve 41.5mg in 5mL of pH7 phosphate buffer

Preparation of working solution (10 -5 M):-
Dilute 0.01mL Stock Solution in 10mL of pH7 phosphate buffer (i.e. 1:1000)

Risk Assessment

Phloxine may irritate the eyes. Wash hands after use.

Measurement Conditions
Syringe Ratio: 1:1 (both syringes 2.5mL)  
BSA conc. in cell:    5x10 -6 M
Phloxine conc. in cell:    5x10 -6 M
Excitation wavelength:    515nm
Cut-off filter(s): APFF550
Acquisition period: 100s (with oversampling)
Time constant: 1ms
Number of data points: 1000

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