Biomedical subjects

R N Zuckermann

Publications and source records attributed to R N Zuckermann.

22 records · Page 2Linked to original sources

PubMed1992

Identification of highest-affinity ligands by affinity selection from equimolar peptide mixtures generated by robotic synthesis.

A fully automated peptide synthesizer has been constructed that is capable of the simultaneous synthesis of up to 36 individual peptides and the synthesis of equimolar peptide mixtures. The instrument consists of an array of reaction vessels, a series of solenoid valves to control liquid flow, and a Zymark robot to deliver solvents and reagents; all components are computer controlled and coordinated. Equimolar peptide mixtures are obtained by algorithms that automate the mixing and distribution of peptide-resin particles. This technology was used to synthesize a library of 361 peptides, generated by randomizing two critical binding residues of a 10-mer epitope known to bind an anti-human immuno-deficiency virus gp120 monoclonal antibody. Each critical residue was substituted with 19 amino acids consisting of all the natural amino acids except cysteine. The library was synthesized as 19 pools, each containing 19 peptides. Each pool was screened in a solution-phase competition ELISA assay. The 12 most inhibitory peptides in the library were isolated by a rapid affinity-selection method and were identified by mass spectrometry and amino acid analysis. The binding properties of these 12 selected peptides were verified by synthesis and assay of the individual peptides. The two critical residues investigated were found to contribute independently to antibody binding.

Amino Acid Sequence↗

PubMed1992

Design, construction and application of a fully automated equimolar peptide mixture synthesizer.

A fully automated peptide synthesizer has been constructed that is capable of the synthesis of equimolar peptide mixtures and the simultaneous synthesis of 36 individual peptides. The synthesizer was constructed from a workstation of our own design utilizing a Zymark robot arm. A Macintosh II computer coordinates the movements of the robotic arm, the switching of over 40 solenoid valves and the monitoring of sensors in the workstation. The robot hands are used to deliver solvents from pressurized spigot lines and to pipet amino acid solutions from reservoirs to an array of reaction vessels. Liquid dispensing, reagent mixing and solvent removal are controlled from a multifunction I/O board in the computer. The design features of the synthesizer are presented, as well as the characterization of multiple individual peptides, a simple mixture of 19 components, and a complex mixture of 15,625 components.

Amino Acid Sequence↗

PubMed1989

Site-selective cleavage of structured RNA by a staphylococcal nuclease-DNA hybrid.

A hybrid enzyme consisting of an oligodeoxyribonucleotide fused to a unique site on staphylococcal nuclease site-selectively cleaves a number of natural RNAs including Escherichia coli M1 RNA (377 bases), 16S rRNA (1542 bases), and yeast tRNA(Phe). The oligonucleotide directs the nuclease activity of the enzyme to the nucleotides directly adjacent to the complementary target sequence on the substrate RNA. In the case of M1 RNA, hydrolysis occurs primarily at one phosphodiester bond, converting 50% of the starting material to product. Furthermore, the reaction products can be enzymatically manipulated: tRNA(Phe) was cleaved in the anticodon region and was religated to form the full-length tRNA in high yield. Because the specificity of these hybrid enzymes can be easily altered, they should prove to be useful tools for probing RNA structure and function.

Base Sequence↗

PubMedDate not supplied

Automated peptide-resin deprotection/cleavage by a robotic workstation.

A robotic workstation has been constructed that automates the deprotection of peptides with trifluoroacetic acid-labile side-chain protecting groups and cleavage from acid-labile resins. The workstation was constructed around a Zymark robot arm and is integrated with a peptide synthesis workstation. Peptide resin samples are deprotected and cleaved with a trifluoroacetic acid/scavenger cocktail that accommodates all common protecting groups used with Fmoc chemistry. Aqueous-ether continuous extraction is used to remove the scavengers and reaction by-products. The apparatus cleaves a 50-500-mg sample of peptide resin every 2 hours and provides the peptides as an aqueous solution in 10% HOAc. Crude peptides obtained with this apparatus are free from residual scavengers and range in yield from 50%-80%. This method is applicable to all but the most hydrophobic peptides and minimizes human contact with the noxious cleavage reagents.

Amino Acid Sequence↗