Appeal No. 1996-2013
Application No. 07/935,695
polypeptide, is a “single chain antibody fragment[]” in which “the individual heavy and light
chains are linked through a peptide linker” (Examiner’s Answer, page 4). As explained at
page 7 of Huston:
The structure of these synthetic polypeptides is unlike that of naturally
occurring antibodies, fragments thereof, e.g., Fv, or known synthetic
polypeptides or “chimeric antibodies” in that the regions of the BABS
responsible for specificity and affinity of binding, (analogous to native
antibody variable regions) are linked by peptide bonds, expressed from a
single DNA . . . The polypeptides . . . comprise structures patterned after
regions of native antibodies known to be responsible for antigen recognition.
The claimed invention, however, is a non-covalently linked dimer or multimer of
single chain polypeptides (or BABSs, to use Huston’s terminology). We have carefully
reviewed the Huston reference, especially pages 21, 22, 24, 63 through 66, and figures 1B
and 2B (cited by the examiner), but can find no disclosure consistent with non-covalent
linkage between two or more BABSs. The only non-covalent association mentioned in the
reference is within an individual BABS. For example, Huston states on pages 21 through
24 (references to figures omitted):
As is now well known, Fv, the minimum antibody fragment which contains a
complete antigen recognition and binding site, consists of a dimer of one
heavy and one light chain variable domain in noncovalent association.
* * *
The structure of these biosynthetic proteins in the region which impart the
binding properties to the protein is analogous to the Fv region of a natural
antibody. It comprises at least one, and preferably two domains consisting
of amino acids defining V and V -like polypeptide segments connected byH L
a linker which together form the tertiary molecular structure responsible for
affinity and specificity.
* * *
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