why BSA is need ed in some resriction enzymes reaction

[Nick Whte]

In article <owPidDAkUgN0EwGA at demon.co.uk>, "Dr. Duncan Clark"
<duncan at genesys.demon.co.uk> wrote:

> In article <34351DD9.17B7 at ibm.net>, Philip Cheng <lsu0640 at ibm.net>
> writes
> >Hi, there,
> >
> >Does anyone know why BSA is needed in some restriction enzymes reaction?
> >
In terms of mechanism, BSA serves several functions in applications
involving endonucleases.  One function is to coat the inside of the
reaction vial.   Many proteins tend to non-specifically adhere to the
surfaces of glass or plastic tubes.  BSA serves as a sacrificial protein,
sticking to charged binding sites of the reaction vessel and, thereby,
preventing enzyme inactivation via adhesion to the vial.  Second, many
proteins are more stable in a reaction in the presence of other proteins,
BSA creates this molecular "crowding" effect.     Thus, BSA is not an
essential co-factor and is not directly involved in the mechaism of
cleavage; it merely improves the performance of the enzymes through
indirect effects.
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