Drug – bio-affecting and body treating compositions – Antigen – epitope – or other immunospecific immunoeffector – Conjugate or complex
Reexamination Certificate
1993-08-31
2001-01-16
Achutamurthy, Ponnathapu (Department: 1618)
Drug, bio-affecting and body treating compositions
Antigen, epitope, or other immunospecific immunoeffector
Conjugate or complex
C424S001110, C424S001490, C424S178100, C435S007200, C530S345000, C530S391100, C530S403000, C530S404000, C530S405000, C530S406000, C530S408000, C530S409000, C530S410000
Reexamination Certificate
active
06174530
ABSTRACT:
INTRODUCTION
1. Technical Field
The invention relates generally to homogeneous preparation of macromolecules of defined structure containing a plurality of linkages and to reagents and methods for assembly of such molecules.
2. Background
Two methods have traditionally been used to produce complex polymers such as polypeptides. One method relies on relatively uncontrolled polymerization reactions, wherein monomer subunits react to produce large polymers. Using this method, polydisperse macromolecules such as polypeptides and plastics (e.g., polyethylene or nylon) can be produced from monomeric residues such as amino acids or small aliphatic or aromatic organic molecules, respectively. While such polydisperse macromolecules can be relatively easy to produce, the polymeric macroscopic products are not homogeneous at the molecular level but are mixtures of polymers of different lengths and even different composition, e.g., in a random copolymer). Furthermore, the similarity of the homologs produced in such polydisperse preparations makes it difficult or impossible to obtain a single high molecular weight product in pure form.
The second method utilized to obtain complex macromolecules has been the sequential assembly of reversibly protected monomers. This approach can be used to obtain products of defined, typically linear, structure. Unfortunately, the method is limited in the size and, most critically, the complexity of molecules that can be produced. For example, synthesis of defined polypeptides or proteins larger than about 50-80 amino acid residues has been beyond the reach of this technology. Condensation of pre-purified protected peptides, two at a time, is limited by the insolubility of large protected fragments. As a result, synthesis of homogeneous, linear polypeptides, for example, is limited to an upper limit of about 100 amino acid residues.
Mutter et al. (Proteins:Structure, Function and Genetics (1989) 5:13-21) have synthesized branched chain polypeptides by step-wise coupling of protected amino acids to a synthetic, protected, resin-bound peptide template during solid-phase peptide synthesis. Deprotection and cleavage was required to obtain a soluble template-assembled synthetic protein. Also using step-wise, solid phase peptide synthesis, Tam and Zavala (J. Immunol. Meth. (1989) 124:52-61) have built branched chain “lysine tree” templates with peptide branches, referred to as multiple antigen peptides, which were subsequently obtained in soluble, crude form after HF deprotection and cleavage.
Since protecting groups used in polypeptide synthesis generally decreases solubility of the protectable molecule, the ability to condense unprotected polypeptides would provide an improvement in the solubility problem encountered using protected precursors, as well as, minimize harsh deprotection methods needed to achieve a final product. However, the use of unprotected precursors raises the seemingly insurmountable problem of regiospecificity. Therefore, attempts have been made to use regiospecific condensation of unprotected fragments through the use of chemoselective ligation.
Chemoselective ligation requires the use of complementary pairs of reactive groups present at specific sites on the precursor molecules that are being joined. The use of reactive groups having complementary chemical reactivity, such as a thiol group and a bromoacetyl group, results in the formation of a bond in a regiospecific manner. For example, thiol-type chemoselective ligations have been used to prepare a multi-antigenic peptides. In an attempt to avoid harsh deprotection methods and formation of impure products caused by possible steric hindrance between closely spaced growing peptide arms during step-wise solid phase synthesis, Drijfhout and Bloemhoff (
Int. J. Peptide Protein Res
. (1991) 37:27-32) used thiol-type chemoselective coupling by synthesizing a branched “octa-lysine tree” peptide, whose deprotected epsilon amino groups were extended to contain protected sulfhydryl groups (S-acetylmercaptoacetyl) for subsequent coupling to an appropriately modified sulfhydryl-containing antigenic peptide. However, the product obtained had poor characteristics as defined by high performance liquid chromatography and was not fully characterized. More recently, thiol chemistry was used to prepare, in a two-fragment condensation, a totally synthetic, linear, functional HIV protease analog (Schnolzer and Kent (1992) Science 256:221-225).
Unfortunately, thiol chemistry is not completely specific. It is well known, for example, that thiol groups can participate in disulfide bond shuffling. In addition, alkylating agents such as bromoacetyl and maleoyl can react with nucleophilic amino acid groups other than a thiol group. For example, bromoacetyl can react with the thioether side chain of methionine residues, thus limiting the homogeneity and/or complexity of design of the desired product.
Thus, a need exists for homogeneous preparations of easily synthesized homogeneous macromolecules of defined structure having stable ligation linkages and for reagents and methods for constructing these homogeneous preparations of macromolecules that provide ease, rapidity and mildness of synthesis; essentially quantitative yields; versatility in template design; and applicability to construction using a diversity of biochemical classes of compounds. In addition a need exists for homogeneous macromolecules of defined structure that can be designed for desired activity, solubility, conformation and other desirable properties; that present components, such as peptides or oligonucleotides, in non-linear, polyvalent form; that provide higher binding affinity and specificity of interaction; and that are available as homogeneous preparations. The present invention satisfies these needs and provides related advantages as well.
SUMMARY OF THE INVENTION
The present invention is directed to homogeneous preparations of easily synthesized, homogeneous molecules of defined structure containing a plurality of stable oxime linkages formed by parallel assembly and to reagents and methods for rapid and specific parallel assembly of such molecules by chemoselective ligation via oxime formation.
The macromolecules of defined structure comprise an organic molecule to which other molecules will become attached (referred to as a baseplate) having a plurality of oxime linkages, preferably at least three, linked in the same orientation to a plurality of a second organic molecule. Also provided are two reagents for constructing these molecules: baseplates having a plurality of oxime-forming reactive groups and a second organic molecule having an orthogonal reactive group complementary in oxime linkage formation to the oxime forming orthogonal reactive groups present on the baseplate. For the purposes of the present invention, the second organic molecules are alternatively referred to as complementary orthogonal specifically active molecules (“COSM”) and are defined further below. The oxime linkages provide a hydrolytically stable means of joining oligomer or macromolecule subunits. The various reactive groups are referred to herein as “orthogonal” groups, which means that are complementary to each other in reactivity and do not react with other functional groups present in the precursors of the macromolecule being formed.
Also provided by this invention are methods of preparing these molecules by parallel self-assembly comprising chemoselectively linking each of a plurality of orthogonal reactive groups on a baseplate to its complementary reactive orthogonal group present on one of a plurality of a second organic molecule via oxime bond formation. The baseplate and second organic molecules are preferably formed from amino acid resides. In other embodiments, baseplates and/or second organic molecules are formed from or further comprise sugar residues, nucleic acid residues and/or lipids. Preferred baseplates are prepared by controlled, organic chemical syntheses, such as solid phase peptide synthesis (“SPPS”) or the equivalent for nucleic acid
Offord Robin Ewart
Rose Keith
Achutamurthy Ponnathapu
Cooley & Godward LLP
Garcia Maurie E.
Gryphon Sciences
LandOfFree
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