Approximatly 38,000 people in Ireland are affected
by Alzheimer’s, a figure which is growing every day. Because this disease is so
prominent in our society it is important for us, as chemists, to not only be
aware of the facts and statistics, but also what chemical reaction and
imbalances make this disease as devastating and fast acting as it is. In people
diagnosed with dementia and Alzheimer’s, there is shrinking of the Cerebral
Cortex which is the part of the brain that deals with remembering and planning,
But what causes this to happen? Prezi.com
Beta Amyloid, which denote peptides of amino acids,
are crucially involved in Alzheimer’s disease. This protein clumps and tangles
together to form plaques in the fatty membrane that surrounds the nerves of the
brain. These clumps then block signals and communication to and from the brain.
Once these cell membranes are damaged the cells themselves can die which
contributes to the massive loss of brain mass that ultimately brings on
dementia and Alzheimer’s. This Beta Amyloid has no use in the body and is only
a byproduct of a metabolic process.
These plaques form when specific proteins in the
neurons cell membrane are processed differently. Normally, an enzyme called
alpha-secretase snips APP, an amoloid precursor protein, which releases a
fragment while a second enzyme, Gamma secretase, also snips the protein in
another place. These released fragments are thought to benefit neurons.
However, in Alzheimer’s patients, the first snip of the protein is made usually
by another enzyme Beta secretase. This cut combined with the cut made by gamma
secretase results in the release of short fragments called beta amoloid. When
these beta amoloid fragments come together and become insoluble eventually
forming clumps and plaques.
These are created when a protein called Tau is
modified. In normal brain cells, these proteins stabilise structures critical
to cells internal transport system. Nutrients and other cellular cargo are
carried up and down structures called microtubules to all parts of the neuron.
In Alzheimer’s patients , abnormal Tau separates from the microtubules causing
them to fall apart. Strands of this then dislodged Tau clump together to form
tangles inside the neuron which disables the transport system and ultimately
destroys the cell. Pbsnewshour
accessed on 21/01/18)