Why synonymous mutations are not always silent

New modeling shows how synonymous mutations—those that change the DNA sequence of a gene but not the sequence of the encoded protein—can still impact protein production and function. A team of researchers led by Penn ...

Efflux pump inhibitors: Bulking up to beat bacteria

The medical profession is in the midst of losing an arms race. Bacterial antibiotic resistance doesn't just threaten our ability to treat infection but our ability to carry out any treatment where infection is a risk. This ...

Key regulator of cell growth deciphered

The mTOR protein plays a central role in cell growth, proliferation and survival. Its activity varies according to the availability of nutrients and some growth factors, including hormones. This protein is implicated in several ...

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 ...

Newly discovered process brings immune cells up to speed

Cancer cells use an unusual mechanism to migrate into new tissue and form metastases there. The same process probably also keeps some immune cells on their toes. This is the result of a recent study led by the University ...

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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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