Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The blue blood of the emperor scorpion x-rayed

22.06.2012
Biologists from Mainz University are the first to successfully crystallize the hemocyanin of the emperor scorpion to shed new light on the structure and active site of the giant oxygen transport protein

The emperor scorpion (Pandinus imperator) is not only one of the biggest scorpions in the world, but it also has one remarkably large protein, namely hemocyanin. Hemocyanin is a protein complex made up of 24 subunits that functions as blood pigment. It is one of the largest known proteins, comparable in size to ribosomes or even small viruses.


Hemocyanin of the emperor scorpion: model of the 24-meric protein complex and electron density at the active site where oxygen binding takes place.
Abb./©: E. Jaenicke et al (2012), PLoS One 7(3):e32548

For the first time ever, scientists from Johannes Gutenberg University Mainz in Germany have now successfully grown crystals from the emperor scorpion’s hemocyanin. With the help of x-rays, these crystals allow for a more precise analysis of the structure of the protein. Up to now, cryo-electron microscopy has primarily been used to examine large protein structures such as hemocyanin.

This method has its disadvantages, however, because its resolution is not sufficient to be able to differentiate between single atoms. With x-ray crystallography, on the other hand, protein structure can be more precisely determined. It is even possible to determine the spatial arrangement of individual atoms. Scientists rely on this knowledge about the detailed molecular structure of these protein complexes in order to be able to understand how these proteins function.

Hemocyanins are extraordinarily large respiratory proteins that transport oxygen in the blood of mollusks and arthropods. While these blue blood proteins bind oxygen between two copper atoms, human hemoglobin binds oxygen to iron atoms. Hemocyanin fascinates biologists because, depending on the animal species, up to 160 oxygen binding sites within a single protein complex must communicate with one another in order to bind, transport, and release oxygen in the blood. Referred to as cooperativity, this phenomenon occurs only in nature and could potentially be used in nanotechnology applications to build molecular switches. Structure determination at an atomic resolution is necessary in order to be able to understand this process in detail.

For the first time ever, Professor Dr. Elmar Jaenicke from the Institute of Molecular Biophysics at Johannes Gutenberg University Mainz has managed to crystallize the blue hemocyanin protein complex from the emperor scorpion. This is the decisive first step toward successful x-ray structure determination because protein crystals are necessary to diffract x-rays so that the structure of the protein can be determined. Crystallization, however, is especially difficult for large protein complexes. "It is a little bit like a game of chance," Jaenicke describes the crystallization process, because the process is dependent on a number of factors such as the pH-level, the salinity of the solution, or the temperature. "The decisive step is always crystal nucleation," which, according to Jaenicke, can take months and requires a lot of patience. Sometimes, it even takes several years to optimize the conditions for crystallization. This is the reason why so far only a handful of molecular structures of very large protein complexes have been solved using x-ray structure determination worldwide. In fact, one of these structural analyses – namely that of the ribosome – was awarded the Nobel Prize in 2009.

The crystals are measured in the x-ray beam, and the structure is then determined through complex calculations based on the scattered x-rays. At first, Jaenicke and his team of scientists were able to attain a mid-resolution (6.5 ångströms) structure for the emperor scorpion's protein with which secondary structures such as α-helices could be seen, but other elements, such as single amino acids, could not yet be ascertained. In layman's terms: If the protein is a brick house and a telescope is used to try to look at its structure from far away, the windows, doors, and the mailbox would be visible at the current resolution, but the arrangement of the individual bricks would not. "This was our starting point and now we can already see parts of the active site of the molecule. With further improvements to our crystals, we are well on our way to achieving an atomic resolution that is not possible with any other method." According to Jaenicke, the oxygen binding protein from the emperor scorpion would then be one of the five largest structures to have been deciphered using x-ray structure analysis to date.

Johannes Gutenberg University Mainz has the ideal infrastructure to support this type of structural research on very large protein complexes which can only be done at a few research institutes around the world. In Mainz, x-ray structure determination projects in the research groups of Professor Dr. Heinz Decker and Professor Dr. Elmar Jaenicke at the Institute of Molecular Biophysics cover the atomic resolution range, cryo-electron microscopy studies in the research group of Professor Dr. Jürgen Markl at the Institute of Zoology take care of the mid-resolution range. The new rotating anode x-ray generator used at the Institute of Molecular Biophysics is also ideal for determination of the structure of these giant molecules because it produces focused x-ray beams with an intensity comparable to that of second-generation synchrotron beamlines.

Petra Giegerich | idw
Further information:
http://www.uni-mainz.de/eng/15460.php
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0032548

More articles from Life Sciences:

nachricht Water forms 'spine of hydration' around DNA, group finds
26.05.2017 | Cornell University

nachricht How herpesviruses win the footrace against the immune system
26.05.2017 | Helmholtz-Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

How herpesviruses win the footrace against the immune system

26.05.2017 | Life Sciences

Water forms 'spine of hydration' around DNA, group finds

26.05.2017 | Life Sciences

First Juno science results supported by University of Leicester's Jupiter 'forecast'

26.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>