Showing papers in "Advances in Protein Chemistry in 1967"

Crystal structures of metal-peptide complexes.

Abstract: Publisher Summary This chapter discusses crystal structures of metal–peptide complexes. Most of the crystal-structure analyses of metal–amino acid and metal–peptide complexes have been carried out on the assumption that such complexes act as models for the metal-binding sites on proteins. Crystal-structure analyses show that the geometrical features of metal complexes of amino acids, peptides and imidazole are related in systematic ways to the chemical structure, which the complexes have in the crystalline state. Moreover, the transfer of geometrical information from crystal-structure analyses to species that exist in solution depends on the assumption that the complexes found in crystals are present also in the solutions from which the crystals grow. This chapter illustrates that, the existence of cis-trans isomers coordination isomers, optical isomers, and dimeric species in the crystalline complexes emphasizes the variety of species, which must be considered when equations are written to represent metal–peptide equilibria in solution.

Covalent labeling of active sites.

Abstract: Publisher Summary This chapter deals with the covalent labeling of active sites. The active sites are three dimensional structures specially adapted to their specific ligands. This chapter illustrates that three types of protein are involved in the direct catalytic interaction with the specific substrate. The binding of specific ligands to these sites affects the catalytic function of the enzyme indirectly. The chapter explains that by the concerted application of a variety of labeling techniques, sequences of amino acid residues in and near active sites can be determined; mapping of the active sites to reveal some of the three-dimensional structure of the molecule can be achieved; and other problems can be attacked. The chapter concludes by exploring that this approach engages the interest of an increasing number of protein chemists and biologists in the near future.

Crystal structure studies of amino acids and peptides.

Abstract: Publisher Summary This chapter discusses the crystal structure studies of amino acids and peptides. It describes the structures, as elucidated by single-crystal X-ray investigations, of the crystalline amino acids and peptides. The chapter also deals with the powers and limitations of present-day X-ray diffraction techniques. This chapter illustrates that in earlier times only two amino acids and DL-alanine, one Dipeptide, and one cyclic dipeptide has been investigated, and these by X-ray diffraction techniques that were crude by present-day standards. Moreover, the conclusions drawn from these early investigations—that resulted in the formulation of the stable configurations of polypeptide chains—including the a-helix and the pleated sheet and in the derivation of detailed structures for many fibrous proteins are valid. Moreover, the advent of high-speed digital computers has been responsible for a tremendous improvement in the accuracy of crystal-structure investigations; moreover, it has resulted in a parallel increase in the complexity of the molecules.