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MLA Style Manual, formerly titled MLA Style Manual and Guide to Scholarly Publishing in its second (1998) and third edition (2008), was an academic style guide by the United States–based Modern Language Association of America (MLA) first published in 1985. MLA announced in April 2015 that the publication would be discontinued: the third ...
Protein structure is the three-dimensional arrangement of atoms in an amino acid-chain molecule. Proteins are polymers – specifically polypeptides – formed from sequences of amino acids, which are the monomers of the polymer. A single amino acid monomer may also be called a residue, which indicates a
The term "tertiary structure" is often used as synonymous with the term fold. The tertiary structure is what controls the basic function of the protein. Quaternary structure: the structure formed by several protein molecules (polypeptide chains), usually called protein subunits in this context, which function as a single protein complex.
At the top level are all alpha proteins (domains consisting of alpha helices), all beta proteins (domains consisting of beta sheets), and mixed alpha helix/beta sheet proteins. While most proteins adopt a single stable fold, a few proteins can rapidly interconvert between one or more folds. These are referred to as metamorphic proteins. [5]
Currently, solid-state NMR is widely used in the field of structural biology to determine the structure and dynamic nature of proteins (protein NMR). [15] In 1990, Richard Henderson produced the first three-dimensional, high resolution image of bacteriorhodopsin using cryogenic electron microscopy (cryo-EM). [16]
The primary structure of a biopolymer is the exact specification of its atomic composition and the chemical bonds connecting those atoms (including stereochemistry).For a typical unbranched, un-crosslinked biopolymer (such as a molecule of a typical intracellular protein, or of DNA or RNA), the primary structure is equivalent to specifying the sequence of its monomeric subunits, such as amino ...
Proteins are often synthesized in an inactive precursor form; typically, an N-terminal or C-terminal segment blocks the active site of the protein, inhibiting its function. The protein is activated by cleaving off the inhibitory peptide. Some proteins even have the power to cleave themselves.
The following exceptions apply for chemical names, when the article itself is primarily about chemistry: " sulfur " (and related "sulfuric", etc.), " caesium ", and " aluminium " should be spelled this way regardless of the English variation used in the article, being the IUPAC names for these elements;