Solvent content of protein crystals.

Publisher Summary This chapter deals with the recent developments regarding the description and nature of the conformation of proteins and polypeptides with special reference to the stereochemical aspects of the problem. This chapter considers the parameters that are required for an adequate description of a polypeptide chain. This chapter focuses the attention on what may be called “internal parameters”—that is, those which can be defined in terms of the relationships among atoms or units that form the building blocks of the polypeptide chains. This chapter also provides an account of the mathematical method of utilizing these parameters for calculating the coordinates of all the atoms in a suitable frame of reference, so that all the interatomic distances, and bond angles, can be calculated and their consequences worked out. This chapter observes conformations in amino acids, peptides, polypeptides, and proteins.

Conformation of Polypeptides and Proteins

The crystal structure of the light-harvesting antenna complex (LH2) from Rhodopseudomonas acidophila strain 10050 shows that the active assembly consists of two concentric cylinders of helical protein subunits which enclose the pigment molecules Eighteen bacteriochlorophyll a molecules sandwiched between the helices form a continuous overlapping ring, and a further nine are positioned between the outer helices with the bacteriochlorin rings perpendicular to the transmembrane helix axis There is an elegant intertwining of the bacteriochlorophyll phytol chains with carotenoid, which spans the complex

Crystal structure of an integral membrane light-harvesting complex from photosynthetic bacteria

Determination of the secondary structures of proteins by circular dichroism and optical rotatory dispersion.

A three-dimensional structure for the monomeric iron-containing hydrogenase (CpI) from Clostridium pasteurianum was determined to 1.8 angstrom resolution by x-ray crystallography using multiwavelength anomalous dispersion (MAD) phasing. CpI, an enzyme that catalyzes the two-electron reduction of two protons to yield dihydrogen, was found to contain 20 gram atoms of iron per mole of protein, arranged into five distinct [Fe-S] clusters. The probable active-site cluster, previously termed the H-cluster, was found to be an unexpected arrangement of six iron atoms existing as a [4Fe-4S] cubane subcluster covalently bridged by a cysteinate thiol to a [2Fe] subcluster. The iron atoms of the [2Fe] subcluster both exist with an octahedral coordination geometry and are bridged to each other by three non-protein atoms, assigned as two sulfide atoms and one carbonyl or cyanide molecule. This structure provides insights into the mechanism of biological hydrogen activation and has broader implications for [Fe-S] cluster structure and function in biological systems.

https://science.sciencemag.org/content/sci/282/5395/1853.full.pdf

X-ray crystal structure of the Fe-only hydrogenase (CpI) from Clostridium pasteurianum to 1.8 angstrom resolution.

A model is proposed for the structure of an inhibited derivative of an enzyme which hydrolyses proteins. It is based on a map of the electron density distribution at 2 A resolution and interpreted in terms of a previously reported sequence of 241 amino-acids. The map has been derived from a Fourier synthesis of 24,500 terms and represents two crystallographically independent molecules, each of molecular weight 25,000, which are nearly identical in their tertiary structure. The enzyme is composed almost entirely of extended polypeptide chains. A chemical marker unambiguously defines the position of the active centre. The position and orientation of the residues known to be important in catalysis are clearly seen. The mechanism by which the inactive precursor is converted into an active enzyme is revealed.

Three-dimensional Structure of Tosyl-α-chymotrypsin

Structure of crystalline α-chymotrypsin

The first X-ray diffraction pictures of an intact immunoglobulin protein have been obtained.

B.W. Matthews

Papers

Solvent content of protein crystals.

Three-dimensional Structure of Tosyl-α-chymotrypsin

Structure of crystalline α-chymotrypsin

Crystallographic studies of a human immunoglobulin.

An X-ray diffraction study of inhibited derivatives of α-chymotrypsin