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Trace elements:

As precious as gold for your health Dominic Hare and Blaine Roberts

UTS Science in Focus Public Lecture

22 August 2012

UTS: Centre for Forensic Science

First of all, thanks to…


Atoms: Building blocks of the Universe

• The atoms that make up your body, your house, your brand new car are as old as the universe itself

– 14 or so billion years, give or take a few leap years

• How atoms interact with each other determines how matter changes

• Consider then, that the atoms in your body have experienced an eternity of life experiences, sights, smells, sounds, loves, despairs stretching all the way back to the birth of the cosmos.


Chemical properties of atoms

• The number of protons determines which element the atom represents

– Hydrogen has 1, helium has 2, lithium has 3…

• The number of neutrons determines which isotope of the element it represents

– Isotopes have the same properties, but have a slightly different mass

• The number of electrons orbiting the nucleus determines how the atom will react


Electrons and chemical reactions

• How electrons interact with other atoms determines what state an atom exists in, and how they react


What makes you, you


What about the rest?

• 0.1% sulfur, potassium, sodium and chlorine

• 0.006% iron, or 4.2 grams, equivalent to everyone here relative to Sydney’s population

• 0.0001% copper, or 0.072 grams, equivalent to a single grain of rice in 5 buckets of water

• 0.000016% iodine, or 0.02 grams, equivalent to one minute every 6 years

• 0.0000021% cobalt, or 0.000003 grams, equivalent to one drop of water in an Olympic-sized swimming pool


So, how can we possibly measure something that small?


Sodium Potassium Copper

Flame tests


Atomic emission

• As the sample heats in the flame, it gets broken down into it’s constituents

• Electrons moving around the nucleus take in some of the energy from the flame and jump up to a higher orbital

• When these electrons lose energy, they drop back down to their original orbital, emitting light as they go


Atomic emission spectra

Iron

Hydrogen

Mercury


Emission is great, but…

• It often lacks the sensitivity to measure truly trace amounts of something

• How can we measure atoms directly?


On a lighter note…

• Everything weighs something (or, at least officially since July 4, 2012)

• Each and every proton and neutron (and even electron) contributes to an element’s mass

• If phosphorus has 15 protons…

• …and sulfur has 16 protons…

• …an atom of sulfur must weigh more than an atom of phosphorus!


The ICP: A super-charged Bunsen burner


The evolution of the ICP-MS

Inductively coupled plasma-mass spectrometers circa 1980s


You were talking about the body…?

• An ICP-MS gives us a technique that is sensitive enough to be able to measure those minute differences in trace elements in the body

• Cutting-edge ICP-MS is capable of detecting down to parts-per-quadrillion, or one centimetre in 50 round trips to the Sun


Laser ablation


LA-ICP-MS Imaging


Imaging Process

Gas


Imaging Process

ICP

Cones

Ion

lenses Mass

Spec

Ion

Dete

cto

r

Data

Processing


LA-ICP-MS imaging

• Each image gives us quantitative spatial information about trace elements, without the need for excision

1mm Iron


LA-ICP-MS imaging

• We can look at how diseases change trace elements at the micro-meter scale, in situ.

Iron 1mm


Reconstructing iron in the mouse brain


Three-dimensional imaging


Where are we going now?

Trace elements: As precious as gold for your health

Dominic Hare and Blaine Roberts

UTS Science in Focus Public Lecture

22 August 2012

Periodic Table

Abundance in the Universe

What are the Biological Elements of Life?

Lipids

Protein

Carbohydrates

DNA

Central Dogma of Biology

Lipids = membranes

Carbohydrates = energy

Proteins = function

Proteins equal Function

“Pretty much anything a cell does, a protein does it.” –P. Andrew Karplus

3D crystal structure of antioxidant enzyme Cu, Zn

Superoxide Dismutase

Human Genome

-23 chromosomes ~ 22,000 genes

-30-50% of proteins use metal to function

Examples;

Hemoglobin(Fe), Ferritin (Fe), Matrix

metalloprotease (Zn), Xanthine Oxidase (Mo)

….etc.

Vitamin and mineral Supplements

*Daily value not established

We know that many minerals are essential but don’t know how much, why in most cases.

Diseases caused by mineral

Deficiency

Hemochromotosis

Anemia (Fe, Cu)

Acrodermatitis enteropahtica (Zn)

Menke’s disease

(Cu)

Wilson’s disease (Fe)

Malnutrition

Zinc deficiency one of the most common

deficiencies in the world

Over 2 Billion people are estimated to be

deficient in zinc.

-Decreased wound healing

-Impaired immune function

-Impaired growth and neurological

development

-Aggressive behavior

Alzheimer’s disease

•Although named after Alois the disease was describe previously by

Fischer, Bonfiglio, Perusini.

•Accounts for 50-80% of dementia.

•Average patient lives 8 years but can be up to 20 years.

•Projected cost of $20 Trillion dollars over the next 40 years.

Alois Alzheimer Auguste Deter

Alzheimer’s Pathology

Amyloid Plaques

•Pathology begins 10-15 years before disease

symptoms arise (Braak 1996)

•Disease pathology begins in the neocortex and

and progressively spreads through the cortex.

•Massive neuronal loss >50%.

Fe, Cu, K, and Rb are altered in AD Brain.

Amyotrophic Lateral Sclerosis

Zinc-deficient SOD hypothesis for ALS

• Zinc deficient SOD hypothesis

– Without zinc, copper is reduced ~3000x faster than Cu,Zn-SOD (Estevez, AG et al.)

– Many SOD mutants have a reduced affinity for zinc (Crow, JP et al.)

Estevez, A. G., Crow, J. P., Sampson, J. B., Reiter, C., Zhuang, Y., Richardson, G. J., Tarpey, M. M., Barbeito, L. & Beckman, J. S. (1999). Induction

of nitric oxide-dependent apoptosis in motor neurons by zinc-deficient superoxide dismutase. Science 286, 2498-500.

Crow, J. P., Sampson, J. B., Zhuang, Y., Thompson, J. A. & Beckman, J. S. (1997). Decreased zinc affinity of amyotrophic lateral sclerosis-associated

superoxide dismutase mutants leads to enhanced catalysis of tyrosine nitration by peroxynitrite. J Neurochem 69, 1936-44.

e- Ascorbate

O=O O=O•- + NO•

ONOO-

Cu+2 Cu+2 Cu+1 Cu+1

Apoptosis

Cu,Zn Zinc-

deficient

Purified SOD

Measuring Global Metalloprotein Changes with Liquid Chromatography-ICPMS

Size exclusion column

(Agilent BioSEC

4.6x300mm)

Output

Vo Vt

Decreasing MW

Agilent HPLC 1200 Agilent 7700 ICP-MS

Measure Protein Metal Status Directly

Vit

B12

Thyroglobulin,

660kDa

Thyroglobuli

n

aggregate

Ferritin

,

440kD

a

Cu,Zn-

SOD,

32kDa

Catalas

e,

256kDa

V

t

Conalbumi

n,

75kDa

Metalloproteomics = measure of metal bound to protein

Application of Metalloproteomics

The Zn metalloproteome

Each island is a

different Zn-Protein

Micronutrient Information Center

For more information on minerals and vitamins in health and

disease please visit the Linus Pauling Institute Micronutrient

Information Center. (http://lpi.oregonstate.edu/)

Summary

-Proteins are important for cellular function

-Metals are important for protein function

-Deficiencies in minerals can manifest in many ways

-Little is know about the role of minerals in disease

-Metalloproteins play pivotal roles in normal cellular

function and in disease pathologies.

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