Synthetic peptide synthesis

Synthesis. In contrast to pituitary hormones, which usually can be obtained in pure form only after extraction from animal tissues, brain oligopeptides are readily available because of their small size. The synthetic repHca represents the most economical and readily accessible source for the oligopeptides. Two techniques are available for laboratory synthesis of oligopeptides, ie, solution chemistry and soHd-phase peptide synthesis (SPPS). 

M. Bodansky, Peptide Synthesis, 2nd ed., John Wiley Sons, Inc., New York, 1976 J. Meinhofer in Ref. 1, Chapt. 9, p. 297 G. R. Pettit, Synthetic Peptides, Vols. 1—4, Van Nostrand Reinhold, New York, 1980, Vols. 5, 6, Elsevier New York, 1982 E. Shroeder and K. Luebke, The Peptide, Vol. 1, Methods of Peptide Synthesis, Academic Press, New York, 1965 N. Izumiya and co-workers. Fundamentals and Experiments of Peptide Synthesis (in Japanese), Mamzen, Tokyo, Japan, 1987 R. B. Merriheld,/ Mm. Chem. Soc. 85, 2149 (1963) G. Barany and R. B. Merriheld in E. Gross andj. Meinenhofer, eds.. The Peptides Mnalysis, Synthesis, Biology, Vol. 2, Academic Press, New York, 1980, pp. 1—284 G. R. Marshall, Peptides Chemistry and Biology, Escom, Leiden, The Netherlands, 1988. 

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. 

This isoxazolium salt (10 g.) (obtained from the Aldrich Chemical Company, Inc.) was dissolved in 45 ml. of aqueous 1 M hydrochloric acid and reprecipitated by the slow addition with swirling of 400 ml. of acetone. The salt was collected, washed with 300 ml. of acetone, and dried overnight at 25° under reduced pressure (< 1 min.) to give a fluffy product, m.p. 206-208° (decomp.). An isomeric salt, A-ethyl-5-phenylisoxazolium-4 -sulfonate, which may be obtained by the usual synthetic procedure,2 is also useful in peptide synthesis. 

Adamantane can be used to construct peptidic scaffolding and synthesis of artificial proteins. It has been introduced into different types of synthetic peptidic macrocycles, which are useful tools in peptide chemistry and stereochemistry studies and have many other applications as well. Introduction of amino acid-functionalized adamantane to the DNA nanostmctures might lead to construction of DNA-adamantane-amino acid nanostmctures with desirable stiffness and integrity. Diamondoids can be employed to constmct molecular rods, cages, and containers and also for utilization in different methods of self-assembly. In fact, through the development of self-assembly approaches and utilization of diamondoids in these processes, it would be possible to design and constmct novel nanostmctures for effective and specific carriers for each dmg. 

The reaction of dipyridyl disulphide with triphenylphosphine to give the stable phosphonium salt (51) has been used in new methods of phosphorylation (reaction A), in peptide synthesis (reaction B), and in the formation of active esters of cx-amino-acids (reaction C). These reactions appear to have synthetic potential. 

A second strategy is to attach a linker (also referred to as a handle or anchor) to the resin followed by assembly of the molecule. A linker is bifunctional spacer that serves to link the initial synthetic unit to the support in two discrete steps (Fig. 3). To attach a linker to a chloromethyl-PS resin, a phenol functionality such as handle 4 is used to form an ether bond (Fig. 4). To attach the same handle to an amino-functionalized support, acetoxy function 5 or a longer methylene spacer of the corresponding phenol is applied to form an amide bond. Both of these resins perform similarly and only differ in their initial starting resin [4], An alternative approach is to prepare a preformed handle in which the first building block is prederivatized to the linker and this moiety is attached to the resin. For peptide synthesis, this practice is common for the preparation of C-terminal peptide acids in order to reduce the amount of racemization of the a-carbon at the anchoring position [5],... 

Mitchell AR, Kent SBH, Engelhard M, Merrifield R. A new synthetic route to tert-butyloxycarbonylaminoacyl-4-oxymethyl)phenylacetamidomethyl-resin, an improved support for solid-phase peptide synthesis. J Org Chem... 

Tam, J.P. (1988) Synthetic peptide vaccine design Synthesis and properties of a high-density multiple antigenic peptide system. Proc. Natl. Acad. Sci. USA 85, 5409-5413. 

De Visser PC, van Helden M, Filippov DV, van der Marel GA, Drijfhout JW, van Boom JH, Noort D, Overkleeft HS (2003) A novel, Base-Labile Fluorous Amine Protecting Group Synthesis and Use as a Tag in the Purification of Synthetic Peptides. Tetrahedron Lett 44 9013-9016... 

S. Beranova-Giorgianni and D. M. Desiderio. Fast Atom Bombardment Mass Spectrometry of Synthetic Peptides. In Methods in Enzymology Solid-Phase Peptide Synthesis, ed. G. B. Fields. Methods in Enzymology 289. Academic Press, San Diego, 1997, 478-499. 

JP Tam, WF Heath, RB Merrifield. SN2 Deprotection of synthetic peptides with a low concentration of HF in dimethylsulfide evidence and application in peptide synthesis. J Am Chem Soc 105, 6442, 1983. 

JP Tam, RB Merrifield. Strong acid deprotection of synthetic peptides mechanisms and methods, in The Peptides Analysis, Synthesis, Biology, Vol. 9, pp 185-248, Academic Press, New York, 1987. 

Synthetic peptides have been extensively used to study the thermal stability and folding of the triple helix. These peptides can be synthesized as either single chains or cross-linked peptides. Early on, such peptides were synthesized by polycondensation of tri- or hexapeptides, which led to a broad mass distribution that was difficult to separate. With the advances of solid-phase synthesis methods, peptides with defined chain length became available. The most studied collagen-like peptides are (Gly-Pro-Pro) or (Pro-Pro-Gly) and (Gly-Pro-4(if)Hyp) or (Pro-4(if)Hyp-Gly) with n varying from 5 to 15. Sutoh and Noda" " introduced the concept... 

A possibility to overcome the time-consuming solution-phase peptide synthesis, but avoiding specific synthetic problems that cannot be addressed on tbe solid support, is to follow a combined solution-/solid-pbase approach. In such an approach the majority of the peptide sequence is typically assembled on solid support, but critical steps are performed in solution. Below, some exemplary peptides are discussed. 

For such an integrated research activity, differently modified peptides and proteins that carry modifications whose structure can be changed at will through synthesis are invaluable tools. Therefore, the synthesis of the lipidated peptides is an important theme. Lipidated peptides can typically not be accessed via standardized peptide synthesis methods. However, employing the synthetic tools developed and presented here, most types of lipidated peptides can now be synthesized and obtained in pure form. Even though solution-phase approaches still play a significant role in the synthesis of lipidated peptides, the recently developed solid-phase synthesis methods delineate the preferred strategy to access the majority of the required lipidated peptides. 

DKPs are simple and easy to obtain and are quite common by-products of synthetic, spontaneous, and biological formation pathways. DKP formation has been well documented as side reactions of solid-phase and solution-phase peptide synthesis. In addition, DKPs have been shown to be decomposition products of various peptides, proteins, and other commercial pharmaceuticals. Cyclic dipeptides were found to be present in solutions of human growth hormone, bradykinin, histerlin, and solutions of agents within the classes of penicillins and cephalosporins. " DKPs are also enzymatically synthesized in several protists and in members of the plant kingdom. Hydrolysates of proteins and polypeptides often contain these compounds and they are commonly isolated from yeasts, lichens, and fungi. ... 

---