Of oligopeptides

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). 

Finnt, D. F., et al., 1987. Tandem qnadrnpole Fourier tran.sform ma.ss. spectrometry of oligopeptides and small protein.s. Proceedings of the National Academy of Sciences, U.S.A. 84 620—623. 

The Ugi reaction has been successfully applied to the synthesis of oligopeptide derivatives, c.g.. in the construction of a pure tetra-L-valine derivative69. The 2-methylpropanaldimine 2 of (/7)-l-ferroccnyl-2-rnethylpropylarnine with /V-formyl-L-2-amino-3-methylbulanoic acid (3) as the carboxylic acid component and methyl A/-[(.S)-2-isocyano-3-mcthyl-l -nxo-buLyl -L-2-aiuino-3-inethylbutanoate (4) furnishes the diastereomeric valyl-valyl-valyl-valine derivatives in a ratio (S,S[R],S,S)i(S,R[R],S,S) of 91 9. The stereoselectivity of the process can be enhanced to 98.5 1.5 when two equivalents of tetraethylammonium A -formylvalinate are added. 

The —CO—NH - link shown in the red box is called a peptide bond, and each monomer used to form a peptide is called a residue. A typical protein is a polypeptide chain of more than a hundred residues joined through peptide bonds and arranged in a strict order. When only a few amino acid residues are present, we call the molecule an oligopeptide. The artificial sweetening agent aspartame is a type of oligopeptide called a dipeptide because it has two residues. 

Mrksich, M., M.E. Parks, and P.B. Dervan. Hairpin peptide motif A new class of oligopeptides for sequence-specific recognition in the minor-groove of double-helical DNA. J. Am. Chem. Soc. 1994, 116, 7983-7988. 

Historically, after the development of oligopeptide-based vesicles, several groups developed and characterized vesicles using polypeptide hybrid systems consisting of polypeptide and synthetic polymer blocks [17-19]. Soon thereafter, vesicles formed entirely from polypeptides, such as poly(L-lysine)-h-poly(L-leucine) and poly(L-lysine)-h-poly(L-glutamate), were developed [20, 21]. This review will focus on recent developments in the formation of vesicles composed of polypeptide hybrid or polypeptide systems, as well as the potential promise of these systems as effective dmg delivery vehicles. A specific example of a polypeptide-based vesicle is shown in Fig. 1, where the hydrophobic segment is a-helical and the hydrophilic segment is a random coil. 

The cyclization reaction can also be carried out with oligopeptides in the solid phase. Thiohydantoins are obtained analogously by conversion of oligopeptides with ImCSIm [55]... 

Fig. 7.22 Comparison of calculated and observed (x-ray) mean N-C(a)-C bond angles for oligopeptides. Regions of and , of the most populated regions (N>3) of a set of oligopeptides selected as described in the reference quoted above.

Thamotharan, M., Bawani, S. Z., Zhou, X., Adibi, S. A., Hormonal regulation of oligopeptide transporter pept-1 in a human intestinal cell line, Am. J. Physiol. 1999, 276, C821-C826. 

Pan, Y., et al. Expression of a cloned ovine gastrointestinal peptide transporter (oPepTl) in Xenopus oocytes induces uptake of oligopeptides in vitro. J. Nutr. 2001, 131, 1264-1270. 

Tamai, I., et al. The predominant contribution of oligopeptide transporter PepTl to intestinal absorption of beta-lactam antibiotics in the rat small intestine. J. Pharm. Pharmacol. 

B., Frokjaer, S., Influence of oligopeptide transporter binding affinity upon uptake and transport of D-Asp(OBzl)-Ala and Asp(OBzl)-Sar in filter grown Caco-2 monolayers, Int. J. Pharm. 1997, 156, 219-228. 

Harold A. Scheraga, Predicting Three-Dimensional Structures of Oligopeptides. 

F. Brun, J. J. Toulme, and C. Helene, Interactions of aromatic residues of proteins with nucleic acids. Fluorescence studies of the binding of oligopeptides containing tryptophan and tyrosine residues to polynucleotides, Biochemistry 14, 558-563 (1975). 

Haas, E., Wilchek, M., Katchalski-Katzie, E. and Steinbeeg, I. Z. Distribution of end-to-end distances of oligopeptides in solution as estimated by energy transfer. Proc Natl Acad Sd USA 1975, 72, 1807-11. 

DKPs, and 2,6-DKPs can be distinguished on the basis of intramolecular C-N cyclization, tandem reactions, and synthetic methods used. 2,3-DKPs have been used in medicinal chemistry and are found in natural products such as antibiotics (piperacillin), cefoperazone, and bicyclomycin. 2,5-DKPs are common namrally occurring peptide derivatives and are frequently generated as unwanted by-products in the synthesis of oligopeptides. " ... 

Hovgaard, L, and Frokjaer, S. Structure-property model for membrane partitioning of oligopeptides./. Med. Chem. 2000, 43,103-113. 

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