Spiegelmer

L- Ribonukleinsäureaptamere (short L- RNA aptamers ) of the ribonucleic acid ( RNA) related molecules, which are composed of the unnatural L- ribonucleotides. They are artificial oligonucleotides and stereochemical mirror images of natural oligonucleotides. L- Ribonukleinsäureaptamere represent a special form of aptamers and how can these specific molecules, such as proteins that bind via their three-dimensional structure. Thanks to the use of L- nucleotides, they are characterized by a high enzymatic stability. L- Ribonukleinsäureaptamere are being developed as potential drugs under the brand name spiegelmers and tested in clinical trials.

• 2.1 1 mirroring of the target molecule
• 2.2 2 SELEX
• 2.3 3 sequencing and synthesis

Properties

Chemical Properties

L- Ribonukleinsäureaptamere are constructed as mirror images of the stereochemical isomers (enantiomers ) of natural oligonucleotides of L-nucleotides. Nucleotides from which Amptamere including L- Ribonukleinsäureaptamere are constructed so adenosine monophosphate ( AMP), guanosine monophosphate ( GMP), cytidine monophosphate (CMT) and uridine monophosphate (UMP), consisting of a phosphate group, a nucleobase, and a ribose as a carrier of the chiral centers. By replacing the natural D- ribose by its enantiomer, the artificial L- ribose, L- nucleotides occur, the building blocks of L- Ribonukleinsäureaptamere.

Biological Properties

Such other L- aptamers are Ribonukleinsäureaptamere bind capable molecules, such as peptides, proteins and low molecular weight substances. The affinity of L- Ribonukleinsäureaptameren to their target molecules is often in the pico - to nanomolar range and is thus comparable to that of antibodies. L- Ribonukleinsäureaptamere themselves have a low antigenicity. In contrast to other aptamers that can be hydrolytically cleaved by the enzymes, L- Ribonukleinsäureaptamere have a high stability in blood serum. Regardless of which they are rejected due to their low molecular mass, which is below the kidney threshold within a short time by the kidneys. The modified L - Ribonukleinsäureaptamere with a higher molar mass, such as pegylated spiegelmers, show a prolonged plasma half-life.

Production

In contrast to other aptamers L Ribonukleinsäureaptamere can not be obtained designated using the conventional as systematic evolution of ligands by exponential enrichment ( SELEX ) technique, since the L- nucleic acids can not be using enzymatic methods such as the polymerase chain reaction amplified. Therefore, the selection via the detour of conventional D- nucleic acids using mirrored target molecules occurs.

1 Reflection of the target molecule

In the first step, a mirror image of the target molecule is produced artificially. In the case of peptides and small proteins, these synthetic artificial using D-amino acids, the enantiomers of the natural amino acids, prepared by the peptide synthesis. The target molecule is a larger protein, it may optionally be produced using D -amino acids, the mirror image of the epitope using peptide synthesis.

2 SELEX

A conventional, consisting of up to 1016 different oligonucleotides molecule library serves as a starting point for the subsequent SELEX. In cycles of selection using the mirror image of the target molecule, separation, amplification and mutation, where appropriate, the oligonucleotides are isolated which bind best the mirror image of the target molecule.

3 sequencing and synthesis

Using the DNA sequencing the nucleic acid sequence of the oligonucleotides derived from the SELEX method is determined. This information is used for the artificial synthesis of the mirror image of the oligonucleotide, the spiegelmer, using L - nucleotides.

Use

L- Ribonukleinsäureaptamere directed for example against the chemokines CCL2 and CXCL12, the complement component C5a and ghrelin provide potential drugs; they are currently in preclinical or clinical development. Moreover, using it as diagnostics is possible.