Peptide synthesis solid phase method

Contents Introduction. - Structure Determination Amino Acid Analysis. Sequence Determination. Secondary and Tertiary Stmcture. - Peptide Synthesis Formation of the Peptide Bond. Protection of Functional Groups. Undesired Reactions during Synthesis. Racemization. Design of Schemes for Peptide Synthesis. Solid Phase Peptide Synthesis. - Methods of Facilitation. Analysis and Characterization of Synthetic Peptides. -Subject Index. 

Solid Phase Peptide Synthesis The Mernfield Method... 

SOLID-PHASE PEPTIDE SYNTHESIS THE MERRIFIELD METHOD... 

Solid phase peptide synthesis does not solve all purification problems however Even if every coupling step m the ribonuclease synthesis proceeded in 99% yield the product would be contaminated with many different peptides containing 123 ammo acids 122 ammo acids and so on Thus Memfield and Gutte s six weeks of synthesis was fol lowed by four months spent m purifying the final product The technique has since been refined to the point that yields at the 99% level and greater are achieved with current instrumentation and thousands of peptides and peptide analogs have been prepared by the solid phase method... 

Memfield s concept of a solid phase method for peptide synthesis and his devel opment of methods for carrying it out set the stage for an entirely new way to do chem ical reactions Solid phase synthesis has been extended to include numerous other classes of compounds and has helped spawn a whole new field called combinatorial chemistry Combinatorial synthesis allows a chemist using solid phase techniques to prepare hun dreds of related compounds (called libraries) at a time It is one of the most active areas of organic synthesis especially m the pharmaceutical industry... 

FIGURE 27 15 Peptide synthesis by the solid phase method Ammo acid residues are attached sequentially beginning at the C terminus... 

Merrifield was awarded the 1984 Nobel Prize in chemistry for developing the solid-phase method of peptide synthesis. 

Automated Peptide Synthesis The Merrifield Solid-Phase Method 1037... 

Peptide synthesis requires the use of selective protecting groups. An N-protected amino acid with a free carboxyl group is coupled to an O-protected amino acid with a free amino group in the presence of dicydohexvlcarbodi-imide (DCC). Amide formation occurs, the protecting groups are removed, and the sequence is repeated. Amines are usually protected as their teit-butoxy-carbonyl (Boc) derivatives, and acids are protected as esters. This synthetic sequence is often carried out by the Merrifield solid-phase method, in which the peptide is esterified to an insoluble polymeric support. 

NBD derivatives are building blocks in efficient solid-phase method for the synthesis of differently lipidated and additionally modified peptides <2004AGE5839>. 

RB Merrifield, AR Mitchell, JE Clarke. Detection and prevention of urethane acylation during solid-phase peptide synthesis by anhydride methods. J Org Chem 39, 660, 1974. 

In general, solid-phase synthesis, rather than solution-phase synthesis, can be the preferred method for the generation of combinatorial libraries because of the greater abihty to automate a solid-phase protocol, primarily due to the use of excess reagents in solution to effect cleaner reactions and to the ease of workup by simple filtration. The solid-phase method of peptide synthesis has had many notable successes. However, the preparation of peptides containing more than 20 amino acids in length using the solid-phase technique often causes major problems in that very extensive purification of the final product is needed. 

The solid-phase method was tested with the synthesis of many small peptides,[19] including bradykinin, angiotensin, desaminooxytocin, and the 20-residue S-peptide of ribonuclease A, and was found to be useful and efficient. 

It is of some interest to note that 24 of the starting fragments were prepared by solid-phase methods in order to simplify and accelerate the synthesis. This confirms what we have believed for a long time, i.e. that the various approaches (chemical, enzymatic, and biological) to the synthesis of peptides and proteins are not mutually exclusive but, rather, they can complement one another when judiciously selected for the particular problem at hand. 

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