Multipin method

Ede NJ, Bray AM. A simple linker for the attachment of aldehydes to the solid phase. Application to solid phase synthesis by the Multipin method. Tetrahedron Lett 1997 38 7119-7122. 

Using the Multipin method, Gilbertson then synthesized 27 undecapeptides on solid phase, which were presumed to have a helical conformation. This was induced by frequent use of the a-alkylated amino acid aminoisobutyric acid. The phosphine-thiooxide-containing residues were positioned in the i and i + 4 positions, which would lead to the two phosphines being adjacent in the helical peptide chain. In addition, Gilbertson synthesized 36 peptides containing phosphines in the i and i + 1 positions. 

Crowns can be locked into an array format for multiple parallel handling and ready identification (i.e., the Multipin method, as shown in Figure 6.1). 

Maeji, N. J. Valerio, R. M. Bray, A. M. Campbell, R. A. Geysen, H. M. Grafted Supports Used with the Multipin Method of Peptide Synthesis, Reactive Polymers 1994, 22, 203. 

Ede, N. J. Bray, A. M. A Simple Linker for the Attachment of Aldehydes to the Solid Phase. Application to Solid Phase Synthesis by the Multipin Method, Tetrahedron Lett. 1997, 38, 7119. 

Bray AM, Jhingran AG, Valerio RM, Maeji NJ, Simultaneous multiple synthesis of peptide amides by multipin method. Application of vapor-phase ammonolysis, J. Org. Chem., 59 2197-2203, 1994. 

A useful vapor-phase ammonolysis has been developed for simultaneous multiple synthesis of peptide amides by both the resin and multipin methods. Pins or peptide-resins are deprotected and washed with CHjCb, DMF, and CH2CI2, and are then air-dried. A bottle of NH3/THF (3 7 v/v, 50-100 mL) was cooled to —78 °C and placed in a well-greased desiccator together with the multipin pin holders (1-4) or the open vials containing resins (130mg/vial). The desiccator was clamped shut, partially evacuated (10 s), and then left to stand at 20°C for 24 h. After this time, the multipin pin holders and the resins were removed from the dessicator and allowed to stand for 30 min. Qeaved peptides were eluted from the pins by immersing them in MeCN/H20 (4 6) for 3 h, or from the resins by washing with AcOH/MeCN/HjO (3 4 3, 5 x ImL). 

L Dapremont, AM Valerio, AM Bray, KM Stewart, TJ Mason, AW Wang, NJ Maeji. Multiple synthesis using the multipin method. Physiol Chem and Phys Med NMR 339-343, 1995. 

The execution of the parallel synthesis of up to 96 single compounds by the Multipin method involves pipetting the reactants to each well of a 96-well microtiter plate. The pin array is then placed on top of the plate and the resin is allowed to incubate with the reactants to perform the coupling step. The reaction temperature can be raised to 90°C by placing the reaction block into an incubator. Following each reaction step, the pin array is removed and treated in batch to wash the solid support. These operations are repeated until the desired combinatorial synthesis is completed. The resulting compounds can then be removed from the pins into individual wells on a microtiter plate, each of which ideally contains one single compound. 

Combinatorial libraries are prepared by the (1) parallel synthesis of arrays, (2) split-pool method, (3) biological method, or (4) spatially addressable parallel synthesis [74,78-80]. Parallel synthesis is carried out by the simultaneous synthesis of an array of different compounds. Several methods are available. In the multipin method, the peptide synthesis is carried out on polyethylene rods that have attached protected amino acids [81]. The amino acid sequence of a synthesized peptide on a particular pin depends on the order in which the amino acids are added. The number of products synthesized is the same as the number of pins. Another version of parallel synthesis, known as the teabag method, uses resin-filled bags in place of pins [74]. By pooling the resin portions from the appropriate bags, followed by redistribution and further coupling with a specific amino acid, a peptide library can be synthesized. The SPOT method uses a cellulose paper membrane as a solid support, which acts as an open reactor. Respective reagent solutions are pipetted onto several spots to synthesize as many peptides as the spots chosen [74,82]. 

The protocols presented here describe the synthesis of a single peptide aldehyde. Synthesis using the Multipin method can be performed in a variety of vessels depending on the scale of synthesis. Sealable polypropylene... 

The Multipin method is an effective, low cost, simultaneous multiple peptide synthesis technology which gives researchers ready access to large... 

The pin consists of a radiation-grafted polypropylene crown fitted to an inert polypropylene stem . Graft polymers used with the Multipin system include polystyrene, a methacrylamide copolymer (38), and poly(hydroxyethyl methacrylate) (34) (HEMA). We have found that the HEMA surface is best suited to peptide synthesis. Historically, peptides were prepared in a non-cleavable format on the crown surface for epitope mapping applications (39). Over the past decade, however, most peptides prepared by the Multipin method have been synthesized on cleavable linkers. The linkers used for peptide synthesis are outlined below. 

Figure 1 summarizes the linkers used for peptide synthesis by the Multipin method. Most carboxylic acids are prepared on the 4-(hydroxymethyl)-phenoxyacetic acid handle 1 (40). To avoid diketopiperazine formation during the synthesis of peptides containing a C-terminal Pro residue, the sterically hindered linker 2 is used (41). To minimize the risk of racemization dining linker derivatization. Asp and Glu are linked via their side-chain functionality, as shown in 3. Similarly, Asn and Gin are prepared by coupling Fmoc-Asp-OrBu and Fmoc-Glu-OiBu, respectively, to the Rink linker 4 (42). 

At the completion of peptide assembly, the peptides are side-chain de-protected and cleaved, usually concurrently. In the Multipin method, cleavage is performed using TFA solution containing scavengers. Cleavage... 

---