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Polymer Science and Engineering: The Shifting Research Frontiers
the art is exemplified by Merrifield-type syntheses, in which polypeptides are synthesized one amino acid at a time on an insoluble support composed of polypeptides and polynucleic acids. This method is limited to preparation of short chains (less than 50 amino acid groups) and small quantities. Techniques that allow similar controlled synthesis on a much larger scale would be revolutionary.
The study of informational polymers aims to determine the specific shapes of biological polymers at atomic and nanometer resolution, the relationship between structure and function, and how the structure and function arise from the underlying interatomic forces of nature. Because these are the same goals as in the study of synthetic polymers, the topics of biomaterial-related polymer science and engineering cut across all the areas of this report.
Biopolymers in Molecular Recognition
A major goal of science is to learn how one molecule binds, recognizes, and interacts with another molecule. If the principles that control the binding and recognition events were understood, we could design activators for biomolecules and drugs, understand biological regulation, and improve separation methods. Major strides are occurring in the following areas: (1) Structures of biomolecule complexes are becoming available, including antibody-antigen complexes, ligands with proteins or DNA or RNA, proteins with DNA, and viruses and ribosome assemblies. (2) Computer programs are being developed to allow databases to be searched to find promising binding candidate molecules. (3) Combinatoric peptide templates, which are arrays of very large numbers of different peptides attached to surfaces, are allowing rapid screening of large numbers of possible binding agents for a specific bioprobe and have the potential to speed up drug design by many orders of magnitude.
Biopolymers in Biological Motion
The cellular machinery for motion is complex and varied. For example, some bacteria are propelled by their flagellae, which act like small rotors. Vertebrate muscle motion depends on the actomyosin system, whose major components are the proteins actin and myosin. The myosin fibers move along the actin fibers, powered by cellular processes involving adenosinetriphosphate (ATP). The exact motions of the myosin molecules are not yet understood. The structures of both the actin and the myosin proteins have recently been determined by crystallography. New methods have recently been developed that probe forces and motions, including a mobility assay for watching the motions of muscle and related proteins under the microscope, ''optical tweezers" for measuring forces, and electron spin resonance experiments for detecting conformational changes. Major advances are happening very rapidly now.