New protein linked to early-onset dementia identified

Most neurodegenerative diseases, including dementias, involve proteins aggregating into filaments called amyloids. In most of these diseases, researchers have identified the proteins that aggregate, allowing them to target ...

Oncology & Cancer

First-in-class targeted microRNA therapy slows cancer tumor growth

A new cancer therapy developed by Purdue University researchers attacks tumors by tricking cancer cells into absorbing a snippet of RNA that naturally blocks cell division. As reported in Oncogene, tumors treated with the ...

Diseases, Conditions, Syndromes

Even as SARS-CoV-2 mutates, some human antibodies fight back

An anonymous San Diego resident has become a fascinating example of how the human immune system fights SARS-CoV-2. In a new investigation, scientists from La Jolla Institute for Immunology (LJI) have shown how antibodies, ...

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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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