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 The world's tiniest first responders
21.06.2018 | University of Southern California

nachricht A new toxin in Cholera bacteria discovered by scientists in Umeå
21.06.2018 | Schwedischer Forschungsrat - The Swedish Research Council

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Better model of water under extreme conditions could aid understanding of Earth's mantle

21.06.2018 | Earth Sciences

What are the effects of coral reef marine protected areas?

21.06.2018 | Life Sciences

The Janus head of the South Asian monsoon

21.06.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>