Peptides methods development strategy

In any methods development strategy (Applied Biosystems, 1994) one attempts to maximize the separation properties of the technique while exploiting the unique chemical properties of the analytes to obtain the best separation possible. For the electrophoretic separation of peptides, the most critical factor that may affect the ability to achieve an adequate separation is the relationship of net charge and separation pH. The examples below illustrate this relationship for a small set of peptides and then elaborate on optimization parameters and pitfalls with a more complex system. 

The use of CE methods for routine quality control of synthetic or recombinant peptides-proteins necessitates optimization strategies for rapid method development. Ideally, the methods should be simple, fast, and robust. Because capillary electrophoresis in the zone format is the most simplistic, initial efforts should be directed toward the use of a simple buffer system [61]. The high efficiency and reproducibility in protein-pep-tide separations demands that interactions between the analyte and capillary wall be neglible. The use of low-pH buffers generally results in enhanced reproduciblity, and hence ruggedness, as slight variations in the capillary surface will have little impact on the already suppressed EOF. 

Abstract This article summarizes recent developments in the synthesis of polypeptides and hybrid peptide copolymers. Traditional methods used to polymerize -amino acid-N-carboxyanhydrides (NCAs) are described, and limitations in the utility of these systems for the preparation of polypeptides are discussed. Recently developed initiators and methods are also discussed that allow polypeptide synthesis with good control over chain length, chain length distribution, and chain-end functionality. The latter feature is particularly useful for the preparation of polypeptide hybrid copolymers. The methods and strategies for the preparation of such hybrid copolymers are described, as well as analysis of the synthetic scope of the different methods. Finally, issues relating to obtaining these highly functional copolymers in pure form are detailed. 

The literature on applications of NMR to problems in molecular biology now encompasses several thousand entries, and space limitations preclude a complete exposition of the subject in this article. Amino acids, peptides, proteins, nucleic acids and their constituents, polysaccharides, phospholipids, membranes, and a large range of biologically active compounds have been extensively studied by NMR. The reader interested in doing research in this field will find it necessary to consult a more extensive treatise (see, e.g.. Refs. 60, 61). Our aim here is to give only a brief introduction to the types of problems that have been studied and an outline of the methods and strategies developed for this purpose. 

We have previously developed an in vivo selection method in which peptides that home to specific vascular beds are selected after intravenous administration of a phage display random peptide library [5]. This strategy revealed a vascular address system that allows tissue-specific targeting of normal blood vessels [6-8] and angiogenesis-related targeting of tumor blood vessels [3, 6, 9-12]. While the biologi-... 

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