Frog protein may mitigate dangers posed by toxic marine microbes

A new study from UC San Francisco suggests that a protein found in the common bullfrog may one day be used to detect and neutralize a poisonous compound produced by red tides and other harmful algal blooms. The discovery ...

'Fishing a line' coupled with clockwork for daily rhythm

Organisms on this planet, including human beings, exhibit a biological rhythm that repeats about every 24 hours to adapt to the daily environmental alteration caused by the rotation of the earth. This circadian rhythm is ...

Nuclear pore complex outer rings: No longer 'one size fits all'

In eukaryotic cells, the nucleus is walled off from the rest of the cell by the nuclear envelope. All transport into and out of the nucleus occurs via cylindrical channels called nuclear pore complexes (NPCs) that penetrate ...

Gold adds the shine of reversible assembly to protein cages

Protein cages—capsule-like structures made up of numerous protein molecules—perform roles in nature that have inspired their application in areas such as drug delivery. Their controlled assembly is therefore of particular ...

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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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