The unbinding probability

Another quantity related to the number of molecule present on the surface is the unbinding probability Punbinding that is usually defined as a ratio between the number of curves with the unbinding events to the total number of the recorded force curves:

Its value corresponds directly to the number of molecules present on a surface of living cells, which can vary depending on the complex or cell types [53] (see also Table 5.2).

Table 5.2 The unbinding probability determined for non-malignant HCV29 and malignant T24 bladder cells [53]

Cells

Lectin-glycan

complex

Number of force curves

Number of unbinding events

Unbinding

probability

HCV29

ConA1-mannose

3982

438

0.110

HCV29

SNA2-sialic acid

4057

215

0.053

T24

ConA-mannose

3983

111

0.028

T24

SNA-sialic acid

4095

344

0.084

1ConA-lectin from Canavalia ensiformis. 2SNA-lectin from Sambucus nigra.

The determination of the unbinding probability gives only the robust estimation of the number of receptors present on the investigated cells’ surfaces. This parameter does not describe the receptor distribution over the cell surface. The same unbinding probability value can be obtained for receptors randomly distributed over a certain area as well as in the case when receptors are grouped around one place in the same area.

 
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