Evidence for new theory of genetic recombination

In most higher organisms, including humans, every cell carries two versions of each gene, which are referred to as alleles. Each parent passes on one allele to each offspring. As they are linked together on chromosomes, adjacent ...

Puzzling out the structure of a molecular giant

Combining AlphaFold2 with experimental and computational techniques has helped scientists figure out the human nuclear pore complex's architecture in greater detail than ever before.

New technology solves mystery of respiration in Tetrahymena

Tetrahymena, a tiny single celled-organism, turns out to be hiding a surprising secret: it's doing respiration—using oxygen to generate cellular energy—differently from other organisms such as plants, animals or yeasts. ...

AI algorithm solves structural biology challenges

Determining the 3-D shapes of biological molecules is one of the hardest problems in modern biology and medical discovery. Companies and research institutions often spend millions of dollars to determine a molecular structure—and ...

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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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