Balancing mitochondrial dynamics in Alzheimer's disease

(Medical Xpress)—Many diseases are multifactorial and can not be understood by simple molecular associations alone. Alzheimer's disease (AD)is associated with toxic transformations in two classes of protein,amyloid beta ...

Alzheimer's disease & dementia

Scientists identify molecular trigger for Alzheimer's disease

Researchers have pinpointed a catalytic trigger for the onset of Alzheimer's disease – when the fundamental structure of a protein molecule changes to cause a chain reaction that leads to the death of neurons in the brain.

Medical research

Researchers describe elusive replication machinery of flu viruses

Scientists at The Scripps Research Institute (TSRI) have made a major advance in understanding how flu viruses replicate within infected cells. The researchers used cutting-edge molecular biology and electron-microscopy techniques ...


New study finds HIV Achilles Heel

(Medical Xpress) -- A new study published in the Proceedings of the National Academy of Sciences shows how scientists have used a mathematical tool to possibly identify an Achilles heel in HIV which may lead to new vaccines ...

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Protein structure

Proteins are an important class of biological macromolecules present in all biological organisms, made up of such elements as carbon, hydrogen, nitrogen, oxygen, and sulphur. All proteins are polymers of amino acids. The polymers, also known as polypeptides, consist of a sequence of 20 different L-α-amino acids, also referred to as residues. For chains under 40 residues the term peptide is frequently used instead of protein. To be able to perform their biological function, proteins fold into one, or more, specific spatial conformations, driven by a number of noncovalent interactions such as hydrogen bonding, ionic interactions, Van Der Waals forces and hydrophobic packing. In order to understand the functions of proteins at a molecular level, it is often necessary to determine the three dimensional structure of proteins. This is the topic of the scientific field of structural biology, that employs techniques such as X-ray crystallography or NMR spectroscopy, to determine the structure of proteins.

A number of residues are necessary to perform a particular biochemical function, and around 40-50 residues appears to be the lower limit for a functional domain size. Protein sizes range from this lower limit to several thousand residues in multi-functional or structural proteins. However, the current estimate for the average protein length is around 300 residues. Very large aggregates can be formed from protein subunits, for example many thousand actin molecules assemble into a microfilament.

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