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PubMed1998

Unusual protein-binding specificity and capacity of aza-arenophilic gels.

A number of synthetic aza-arenophilic gels have been synthesized from Sepharose CL-4B, 3,5-dichloro-2,4,6-trifluoropyridine and 4-dimethylaminopyridine. These show high binding capacities for immunoglobulins and enzymes. Under high-salt buffer binding conditions, IgG can be effectively eluted, essentially free of contamination by BSA, using acidic conditions (pH 2.5) or phosphate buffers (pH 7.4) containing nucleophiles. Enzymes can also be readily adsorbed and desorbed. Thus these gels can be reused as supports for the immobilization of enzymes.

Affinity Labels↗
PubMedDate not supplied

Triphosgene: an efficient carbonylating agent for liquid and solid-phase aza-peptide synthesis. Application to the synthesis of two aza-analogues of the AChR MIR decapeptide.

The N alpha/C alphaH exchange in aza-peptides has the advantage of preserving the side chain. Bis(trichloromethyl)carbonate or triphosgene is a solid, stable phosgene substitute which retains its high reactivity. Temperature and coupling times are greatly reduced with reference to other usually recommended carbonylating agents, while purity and yield are increased. It has been used, in both liquid- and solid-phase procedures, for the synthesis of various aza-analogues of dipeptides, tripeptides and decapeptides containing the alanine, aspartic acid and asparagine aza-residue.

Aza Compounds↗
PubMed2000

Design, synthesis, and conformational analysis of azacycloalkane amino acids as conformationally constrained probes for mimicry of peptide secondary structures.

Conformationally constrained amino acid and dipeptide units can serve in mimics of specific secondary structures for studying relationships between peptide conformation and biological activity. A variety of mimics are required to study systematically the structure-activity relationships in biologically relevant peptides. We present our efforts on the design, synthesis, and conformational analysis of a series of rigid surrogates of amino acid and dipeptide units for application within constrained peptide analogues, and for employment as inputs for combinatorial science. Conceived to be general and versatile, our methodology has delivered a variety of azacycloalkane and azabicycloalkane amino acids in enantiomerically pure form, via practical methods, from readily available and inexpensive starting materials.

Amino Acids↗
PubMed2000

A spectroscopic and crystallographic study of polymorphism in an aza-steroid.

The crystal structures of two enantiotropic polymorphs of the aza-steroid finasteride (N-(1-1-di-methylethyl)-3-oxo-4-aza-5 alpha-and rost-1-ene-17 beta-carboxam ide ) have been determined. The solid-state nuclear magnetic resonance spectra, infrared spectra, and physical property data of these two polymorphs are discussed in relation to both their solid-state structures and hydrogen-bonding networks.

Aza Compounds↗
PubMed2000

Synthesis and hybridization properties of oligonucleotides containing polyamines at the C-2 position of purines: a pre-synthetic approach for the incorporation of spermine into oligodeoxynucleotides containing 2-(4,9,13-triazatridecyl)-2'-deoxyguanosine.

We have developed a synthesis of spermine-containing oligonucleotides (ODN-sper) which allows incorporation of multiple polyamine residues. This approach was based on the pertrifluoroacetylated 5'DMT-dGsper phosphoramidite synthon. Its coupling yield with resin-bound ODN decreased dramatically when close to the 3'-end. Optimization of the coupling conditions allowed 22-mer ODNs containing up to six spermine residues to be synthesized. Several ODNs of different sequences with 1-4 pendent spermines could be purified and their hybridization properties were evaluated. Duplex melting temperatures increased linearly with the number of polyamine residues (deltaTm/sper = 3.0 +/- 0.2 degrees C in 100mM NaCl). This compares very favorably with values reported for duplexes of similar initial stability containing other cation-substituted bases. Moreover, the stability increase was neither sequence nor position-dependent, and even contiguous spermine residues did not cross-talk. Extrapolation based on these findings leads to the conclusion that a duplex formed with a 22-mer oligonucleotide containing seven spermine residues would be as stable as genomic DNA, which highlights its potential for DNA strand invasion.

Aza Compounds↗
PubMed2001

Expanded phthalocyanine analogues: synthesis and characterization of new triazole-derived annulenes containing six heterocyclic subunits.

A series of heteroannulenes 3a-f containing four subunits of isoindole, two 1,2,4-triazole moieties, and six aza bridges have been synthesized by dimerization of the corresponding metallated, three-unit intermediates 5a-f. All these 28 pi-electron triazolephthalocyanine derivatives coordinate two metal ions within their central cavity and are the first examples of expanded heterophthalocyanines. Spectroscopic properties of these macrocycles show evidence for extended conjugation and antiaromaticity. The nature of the metal ions plays a definite role in the electronic properties of these derivatives.

Aza Compounds↗