Kinetics of Solute Uptake :

Kinetics of Solute Uptake : 

1] Transporter-Mediated Uptake :

The uptake of solute in presence of transporter.

► The existance of transporter can revealed        by the kinetics of solute uptake.

► If solute (amino acid or suger) was added       at different concentration to a bacterial           suspension and plot the initial rate of               uptake into the cell as a function of the           external concentration of solute.

► The curve is generated which hyperbolic          that approaches a maximum rate.

► The kinetics of transporter mediated               uptake can be rationalized by asauming           that the only signigicant route of entry for       the solute is limited no. of transporter.

► The solute does not passively leak into the     cell to any significant extent.

                   Kinetics of Transport

► The rate at which solute enters to cell is         directly proportional to the function of             transporter that are occupied with solute.

► As the external concentration of solute           increases a progressively larger fraction of     transporter bind solute and rate of                   transporter increases to a maximum rate         ( V_max ) & at the stage there is no unloaded     transporter.

► The Concentration of solute that produces     one half the maximum intial rate of                   transporter is called "Km" or sometimes           (Kt).

► It is frequently assumed to be a measure         of the affinity of the solute for the                     transporter and called "affinity constant".

   How ever it will be referred to here simply       as the solute concentration that given             ½ V_max

► The value of Km is characteristics of                transporter and range from less than one        micromolar to several hundered                        micromolar.