Practical Protein Chemistry - A. Darbre 1989

Prediction of Peptide and Protein Conformation
Introduction

B. ROBSON (Department of Biochemistry, The Medical School, University of Manchester, Oxford Road, Manchester M13 3PL, U.K.)

Early attempts to successfully predict the Conformations of Biomacromolecules boast a history spanning over 30 years. What is the primary lesson learned over this time? It is probably fair to say that predictions cannot be made with absolute certainty based solely on theoretical concepts. Numerous assumptions are required to yield results within a reasonable timeframe through computations that are impossible without The Use of computers. Consequently, a peculiar ambiguity arises: Structure A is preferred over structure B, which nevertheless remains quite plausible until a serious objection is raised. Therefore, the entire purpose of applying a theoretical approach is to enable a definitive Conclusion regarding the preference of one conformation over another when experimental data are taken into account. It is precisely through the incorporation of experimental data that major discoveries in molecular biology were made: the existence of $\alpha$-helices and $\beta$-sheets in Proteins and The Double Helix in DNA was proven. Recently, several other problems have also been successfully resolved: targeted drug design and the Determination of the spatial Introduction/33.html">Structure of Polysaccharides are just two Examples of such successes. In some cases, such as refining crystallographic protein data using energy calculations, the theoretical approach has become standard Procedure. Metaphorically speaking, experiments in biomolecular structure prediction have already outgrown infancy, although they have not yet reached adulthood.

Researchers working on molecular conformation prediction prefer to state that a conformation has been calculated using conformational analysis. This method allows for both predicting and explaining experimental data. Calculating the molecular properties of compounds for which the preferred conformation is far from being the sole mode of structural Organization constitutes the primary task of conformational analysis. Many molecules lack a fixed conformation, which, strictly speaking, is possible only at absolute zero. Molecules of certain oligopeptides, such as Neuropeptides, exhibit a linear and rather flexible structure, rendering the calculation of a single conformation clearly insufficient. In such cases, it is advisable to calculate averaged properties, such as the averaged spin-spin coupling constant, the value of which can be derived from NMR spectroscopy data. Comparing calculated and empirical values enables the interpretation of experimental data in terms of the conformational capabilities of a given compound.

Cell/13.html">Protein Structure Prediction attracts widespread interest, and breakthroughs in this field may also hold socio-economic significance [59, 60]. Predictive Methods in Protein Engineering are now considered part of extensive research programs spanning pharmaceutical, agricultural, and social domains. This circumstance has stimulated advancements in specialized mathematical approaches, which need not be detailed in this review. Subsequent Discussion focuses primarily on the physical foundations and Specific features of the computations performed. Certain important issues related to hardware and technical instrumentation are also discussed [51, 61, 70].