https://zenodo.org/record/1258475/files/article.pdf

Electron transfers in chemistry and biology

Self-Assembly of Discrete Cyclic Nanostructures Mediated by Transition Metals

Publisher Summary This chapter investigates the anatomy and taxonomy of protein structures. A protein is a polypeptide chain made up of amino acid residues linked together in a definite sequence. Amino acids are “handed,” and naturally occurring proteins contain only L-amino acids. A simple mnemonic for that purpose is the “corncrib.” The sequence of side chains determines all that is unique about a particular protein, including its biological function and its specific three-dimensional structure. The major possible routes to knowledge of three-dimensional protein structure are prediction from the amino acid sequence and analysis of spectroscopic measurements such as circular dichroism, laser Raman spectroscopy, and nuclear magnetic resonance. The analysis and discussion of protein structure is based on the results of three-dimensional X-ray crystallography of globular proteins. The basic elements of protein structures are discussed. The most useful level at which protein structures are to be categorized is the domain, as there are many cases of multiple-domain proteins in which each separate domain resembles other entire smaller proteins. The simplest type of stable protein structure consists of polypeptide backbone wrapped more or less uniformly around the outside of a single hydrophobic core. The outline of the taxonomy is also provided in the chapter.

The anatomy and taxonomy of protein structure.

A human IgGI antibody has been reshaped for serotherapy in humans by introducing the six hypervariable regions from the heavy- and light-chain variable domains of a rat antibody directed against human lymphocytes. The reshaped human antibody is as effective as the rat antibody in complement and is more effective in cell-mediated lysis of human lymphocytes.

Reshaping human antibodies for therapy.

Photosynthesis uses light energy to drive the oxidation of water at an oxygen-evolving catalytic site within photosystem II (PSII). We report the structure of PSII of the cyanobacterium Thermosynechococcus elongatus at 3.5 angstrom resolution. We have assigned most of the amino acid residues of this 650-kilodalton dimeric multisubunit complex and refined the structure to reveal its molecular architecture. Consequently, we are able to describe details of the binding sites for cofactors and propose a structure of the oxygen-evolving center (OEC). The data strongly suggest that the OEC contains a cubane-like Mn 3 CaO 4 cluster linked to a fourth Mn by a mono-μ-oxo bridge. The details of the surrounding coordination sphere of the metal cluster and the implications for a possible oxygen-evolving mechanism are discussed.

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Architecture of the Photosynthetic Oxygen-Evolving Center

The environment of the haem group in erythrocruorin (Chironomus thummi).

Erythrocruorin ist das sauerstoff-tibertragende H~mprotein der Larven der Chironomiden (Chironomus thummi, Zuckmticken). Es ist in der K6rperfltissigkeit gelSst und hat wahrscheinlich, wenigstens in einem bestimmten Sauerstoffdruckbereich, Transportund Speicherfunktion [t~. Eine Bestimmung der Terti~irstruktur dieses Proteins ist insbesondere wegen der Vergleichsmaglichkeit mit den bekannten Terti/irstrukturen der S~iugerhgmproteine Myoglobin [21 und H~imoglobin [3] interessant I4]. Die Reindarstellung yon Erythrocruorin erfordert mehrere F~ilIungen und Chromatographien [5, 6]. Es lassen sich bis zu acht verschiedene Erythrocruorine trennen [7]. Die Kristallisation gelang bisher nur bei einer Bande der DEAE-Cellulosetrennung [51, und zwar in der tiblichen Weise durch Aussalzen in Ammonsulfatpuffer. Wir fanden r6ntgenographisch ein Molekulargewicht yon etwa 16000, einen Weft, der deutlich niedriger als der yon Myoglobin (t7 500) ist. Die Sauerstoff-Affinit~itsmessungen am reinen Erythrocruorin I81 liefern eine Kurve, die sehr /ihnlich der yon Myoglobin ist. Die optische Rotationsdispersion [9~ zeigt einen Helixgehalt yon etwa 50% (also nur ~des Helixgehaltes yon Myoglobin). Tabelle I i s t eine Aufstellung der Elementarzellenkonstanten der bisher erhaltenen Kristallmodifikationen. Die trigonale Modifikation, mit der wir die Kristalistrukturanalyse durchftihrten, kristatlisiert zwischen etwa pH 3,9 und pH 7,5, die orthorhombische bei pH 8,5. Schweratomderivate des Erythrocruorins versuchten wir durch Diffusion in die Kristalle in Ammonsulfatpuffer zu erhalten, jedoch ohne ErIolg. Erst nach einem Austausch des Ammonsulfatpuffers gegen Kalium-Natrium-phosphatpuffer It01 fanden wir auf r6ntgenographischem Wege Schweratomsubstitution. Von den etwa 30 untersuchten Schweratomverbindungen stellten sieh ftinf als besonders giinstig heraus:

Kristallstrukturanalyse des Met-Erythrocruorins bei 5,5 Å Auflösung

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/0014-5793%2879%2981251-X

Otto Epp

Papers

The environment of the haem group in erythrocruorin (Chironomus thummi).

Kristallstrukturanalyse des Met-Erythrocruorins bei 5,5 Å Auflösung

The crystallization of protein BL17 from the 50 S ribosomal subunit of Bacillus stearothermophilus.

X-ray studies on antibody fragments.

Crystallographic evidence for structurally similar domains in the human κ-type Bence-Jones protein Rei