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Method for the preparation of a nucleic acid library

  • US 9,115,352 B2
  • Filed: 03/30/2009
  • Issued: 08/25/2015
  • Est. Priority Date: 03/31/2008
  • Status: Expired due to Fees
First Claim
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1. A method for preparing a nucleic acid library comprising a plurality of elements, whereby each element of said nucleic acid library comprises a first stretch of nucleotides, a second stretch of nucleotides and a third stretch of nucleotides, whereby the sequence of the first stretch of nucleotides and of the third stretch of nucleotides are identical in each element of the nucleic acid library and the elements of the nucleic acid library differ in the sequence of the second stretch of nucleotides, the method comprising the following steps:

  • a) providing a first at least partially double-stranded oligonucleotide comprisingaa) a single-stranded overhang, whereby the single-stranded overhang provides for a nucleotide sequence corresponding to the sequence of the first or third stretch of nucleotides of the elements of the nucleic acid library; and

    ab) a recognition site, or part thereof, for a first type IIS restriction enzyme which cuts outside its recognition site;

    b) providing a first oligonucleotide library comprising a plurality of members, whereby each member is a second at least partially double-stranded oligonucleotide comprisingba) a recognition site, or part thereof, for a second type IIS restriction enzyme which cuts outside its recognition site;

    bb) a single-stranded overhang, whereby the single-stranded overhang is the same for each of the members of the first oligonucleotide library and is complementary to the single-stranded overhang of the first at least partially double-stranded oligonucleotide; and

    bc) whereby the members of the first oligonucleotide library differ in the sequence of a stretch of nucleotides and the sequence of said stretch of nucleotides corresponds to the sequence, or part thereof, of the second stretch of nucleotides of the elements of the nucleic acid library, wherein one or more nucleotide positions within the stretch of nucleotides differs at a controlled frequency;

    c) ligating the first at least partially double-stranded oligonucleotide with the members of the first oligonucleotide library via their single-stranded overhangs, whereupon first ligation products are formed;

    d) cutting the first ligation products with said second type IIS restriction enzyme in the nucleic acid sequence of the members of the first oligonucleotide library, and providing for a plurality of first elongated at least partially double-stranded oligonucleotides and for shortened second at least partially double-stranded oligonucleotides;

    e) removing the shortened second at least partially double-stranded oligonucleotides;

    f) providing a second oligonucleotide library comprising a plurality of members, whereby each member is a third at least partially double-stranded oligonucleotide comprisingfa) a recognition site, or part thereof, for a third type IIS restriction enzyme which cuts outside its recognition site;

    fb) a single-stranded overhang, whereby the single-stranded overhang is different for the members of the second oligonucleotide library and whereby such single-stranded overhangs of the third oligonucleotide are complementary to the single-stranded overhangs of the first elongated at least partially double-stranded oligonucleotides; and

    fc) a stretch of nucleotides which is identical in all members and corresponds to the sequence, or part thereof, of the third or first stretch of nucleotides of the elements of the nucleic acid library;

    g) ligating the plurality of first elongated at least partially double-stranded oligonucleotides with the members of the second oligonucleotide library, whereby the single-stranded overhang of the first elongated at least partially double-stranded oligonucleotide is complementary to the overhang of the third at least partially double-stranded oligonucleotides, whereupon second ligation products are formed;

    h) cutting the second ligation products with the third type IIS restriction enzyme in the nucleic acid sequence of the third at least partially double-stranded oligonucleotides, and providing for a plurality of second elongated at least partially double-stranded oligonucleotides and shortened third at least partially double-stranded oligonucleotides;

    i) removing the shortened third at least partially double-stranded oligonucleotides;

    j) providing fourth at least partially double-stranded oligonucleotides comprisingja) a single-stranded overhang, whereby the single-stranded overhang provides for a nucleotide sequence complementary to the single-stranded overhang of the second elongated at least partially double-stranded oligonucleotide; and

    jb) a recognition site, or part thereof, for a fourth type IIS restriction enzyme which cuts outside its recognition site;

    k) ligating the fourth oligonucleotides and the plurality of the second elongated at least partially double-stranded oligonucleotides to form third ligation products;

    l) cutting the third ligation products with the fourth type IIS restriction enzyme in the nucleic acid sequence of the fourth at least partially double-stranded oligonucleotides, and providing for a plurality of third elongated at least partially double-stranded oligonucleotides and shortened fourth at least partially double-stranded oligonucleotides; and

    m) removing the shortened fourth at least partially double-stranded oligonucleotides; and

    n) obtaining the nucleic acid librarywherein the nucleic acid library is a library of nucleic acid molecules coding for a peptide, polypeptide, protein, or functional nucleic acid;

    wherein the peptide, polypeptide, or protein comprises one or several constant regions, and one or several variable regions;

    wherein the one or several of the variable regions is/are encoded by the sequence of the second stretch of nucleotides of the elements of the nucleic acid library; and

    wherein the second stretch of nucleotides of the elements of the nucleic acid library is the only difference between said elements.

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