REPRESENTATION OF UNIQUE SEQUENCES IN LIBRARIES OF RANDOMIZED NUCLEIC-ACIDS

From a library of nucleic acid molecules, which are randomized in part s of their sequence, unique sequence variants can be selected for spec ific properties. The planning of such an in vitro selection experiment requires some consideration regarding how much DNA template or RNA tr anscript should be used initially. The amount applied depends on the n umber of randomized nucleotides and on the expectations of how often e ach conceivable and unique sequence combination should be represented in the experimental pool. We display graphs describing the probability for the representation of unique nucleic acid molecules in a randomiz ed pool as a function of the mean representation k, defined by the rat io of sampled nucleic acid molecules to conceivable sequence combinati ons and we summarize the amounts required to represent unique sequence s with 99% likelihood. The probability of representation, P=1-e(-k) ca n be applied also to 'sub- saturated' pools (k < 1)of nucleic acids wi th long randomized domains, where it is impossible to provide sufficie nt material for full sequence representation.