New study shines light on mysterious giant viruses

In recent years, giant viruses have been unearthed in several of the world's most mysterious locations, from the thawing permafrost of Siberia to locations unknown beneath the Antarctic ice. But don't worry, "The Thing" is ...

Programming with the light switch

In the development of autonomous systems and materials, self-assembling molecular structures controlled by chemical reaction networks are increasingly important. However, there is a lack of simple external mechanisms that ...

Dissecting the mechanism of protein unfolding by SDS

Researchers at the University of Illinois at Urbana-Champaign have used molecular dynamics simulations to understand how sodium dodecyl sulfate causes protein unfolding. SDS is commonly used in labs to separate proteins and ...

Researchers use snake venom to solve structure of muscle protein

Researchers at UT Southwestern Medical Center have uncovered the detailed shape of a key protein involved in muscle contraction. The report, published today in Neuron, may lead to improved understanding of muscle-weakening ...

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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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