Genetics

Reactivating aging stem cells in the brain

As people get older, their neural stem cells lose the ability to proliferate and produce new neurons, leading to a decline in memory function. Researchers at the University of Zurich have now discovered a mechanism linked ...

Diseases, Conditions, Syndromes

Prion diseases: New clues in the structure of prion proteins

Prion diseases are a group of rapidly progressive, fatal and infectious neurodegenerative disorders affecting both humans and animals. Bovine spongiform encephalopathy (BSE) or "mad cow" disease is one of the most famous ...

Diseases, Conditions, Syndromes

NIST clarifies structure of prospective vaccine for respiratory virus

No approved vaccine exists for RSV, a life-threatening virus that attacks the respiratory system. State-of-the-art neutron and X-ray scattering performed at the National Institute of Standards and Technology (NIST) may bring ...

Genetics

AAV capsid-promoter interactions in the non-human primate brain

The phenomenon of AAV capsid-promoter interaction recently seen in the rat central nervous system has now been shown to occur in the non-human primate brain. This interaction can directly determine cell-specific transgene ...

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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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