Navigation Links
Lead with a poisonous electron shield

It has been speculated that lead poisoning may have played a role in the fall of the Roman Empire: it is thought to have been caused by the concentration of grape juice in lead containers. Though the introduction of lead-free gasoline has reduced damage to the environment, the annual production of lead continues to increase worldwide because lead is still used in batteries, glass, and electronic components. However, there has thus far been little research into what, at a molecular level, causes the toxic effects of lead. French researchers have now applied quantum chemistry to very simple enzyme models and gained new insights. As they have reported in Angewandte Chemie, it seems that the lead's "electron shield" is the main culprit.

Lead does the most damage to the nervous system, kidneys, liver, brain, and blood. These kinds of damage are especially severe for children as they can be irreversible. Complexation agents that grab onto the metal cations are used as antidotes. However, these agents are not lead-specific, meaning that they also remove other important metal cations from the body.

C. Gourlaouen and O. Parisel (Laboratoire de Chimie Théorique, Université Paris 6) took a closer look at two proteins to which lead likes to bind. Calmodulin, a calcium-binding protein, plays an important role in regulating and transporting the calcium cation in the human body. A calcium ion binds to seven ligands at the active centers of the enzyme. If one of the four possible calcium ions of calmodulin is replaced by lead, the lead ion remains roughly heptacoordinated, but this active center becomes distorted and inefficient; the three remaining sites get a reduced efficiency.

d-Aminolevulinic acid dehydratase is essential for the biosynthesis of hemoglobin. Inhibition of this enzyme disrupts the formation of blood to the point of anemia. At the active center, a zinc ion binds to four ligands, three of which involve a sulfur atom. When lead replaces z inc, it only binds to the three sulfur atoms. The reason for this is the emerging free electron pair of the lead cation. It acts as an electronic shield on one side, pushing away the fourth ligand. Such a dramatic geometrical distortion at the active center could explain why lead inhibits this enzyme.

The different behavior of lead in these two enzymes demonstrates that it can enter into complexes in which the metal–ligand bonds can either point in all directions, or into only one hemisphere, while the other hemisphere is filled by the free electron pair. This observation may help in the design of future lead-specific antidotes.

Source:John Wiley & Sons, Inc.

Related biology news :

1. CU, USDA team to curb two invasive, poisonous vines
2. Bioelectronic ‘signatures?hold key to DNA mutations
3. Researchers make long DNA wires for future medical and electronic devices
4. UC Davis researchers move biotechnology closer to replacing electronic pacemakers
5. Juiced-up battery fueled by sugar could power small portable electronics

Post Your Comments:

(Date:3/27/2017)... , March 27, 2017  Catholic Health ... and Management Systems Society (HIMSS) Analytics for achieving ... Adoption Model sm . In addition, CHS previously ... U.S. hospitals using an electronic medical record (EMR). ... its high level of EMR usage in an ...
(Date:3/24/2017)... Research and Markets has announced the addition of the ... Industry Forecast to 2025" report to their offering. ... The Global Biometric Vehicle Access ... 15.1% over the next decade to reach approximately $1,580 million by ... and forecasts for all the given segments on global as well ...
(Date:3/23/2017)... Research and Markets has announced the addition of the ... Forecast to 2025" report to their offering. ... The Global Vehicle Anti-Theft System ... over the next decade to reach approximately $14.21 billion by 2025. ... forecasts for all the given segments on global as well as ...
Breaking Biology News(10 mins):
(Date:10/12/2017)... (PRWEB) , ... October 12, 2017 , ... ... Sciences today announced the three Winners and six Finalists of the 2017 Blavatnik ... annually by the Blavatnik Family Foundation and administered by the New York Academy ...
(Date:10/12/2017)... ... 2017 , ... BioMedGPS announces expanded coverage of SmartTRAK Business ... US Hemostats & Sealants. , SmartTRAK’s US Market for Hemostats and Sealants module ... and biologic sealants used in surgical applications. BioMedGPS estimates the market will grow ...
(Date:10/11/2017)... N.C. (PRWEB) , ... October 11, 2017 , ... ... ARCS® Foundation President Andi Purple announced Dr. Suneel I. Sheikh, the co-founder, ... ( ASTER Labs ), Inc. has been selected for membership in ARCS ...
(Date:10/11/2017)... ... October 11, 2017 , ... ComplianceOnline’s Medical Device Summit is back ... 8th June 2018 in San Francisco, CA. The Summit brings together current and former ... CEOs, board directors and government officials from around the world to address key issues ...
Breaking Biology Technology: