Cystine knot
Encyclopedia
A cystine knot is a protein structural motif where two disulfide bridges (cystine
s - formed from pairs of cysteine
molecules) are formed. The sections of polypeptide that occur between them then form a loop through which a third disulfide bond passes, forming a rotaxane
substructure. It occurs in many proteins across many species and provides considerable structural stability.
This motif was first observed in the structure of Nerve Growth Factor
, solved by X-ray crystallography
and published in 1991 by Tom Blundell
in Nature
.
Cystine
Cystine is a dimeric amino acid formed by the oxidation of two cysteine residues that covalently link to make a disulfide bond. This organosulfur compound has the formula 2. It is a white solid, and melts at 247-249 °C...
s - formed from pairs of cysteine
Cysteine
Cysteine is an α-amino acid with the chemical formula HO2CCHCH2SH. It is a non-essential amino acid, which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, which is polar and thus cysteine is usually classified as a hydrophilic amino acid...
molecules) are formed. The sections of polypeptide that occur between them then form a loop through which a third disulfide bond passes, forming a rotaxane
Rotaxane
A rotaxane is a mechanically-interlocked molecular architecture consisting of a "dumbbell shaped molecule" which is threaded through a "macrocycle" . The name is derived from the Latin for wheel and axle...
substructure. It occurs in many proteins across many species and provides considerable structural stability.
This motif was first observed in the structure of Nerve Growth Factor
Nerve growth factor
Nerve growth factor is a small secreted protein that is important for the growth, maintenance, and survival of certain target neurons . It also functions as a signaling molecule. It is perhaps the prototypical growth factor, in that it is one of the first to be described...
, solved by X-ray crystallography
X-ray crystallography
X-ray crystallography is a method of determining the arrangement of atoms within a crystal, in which a beam of X-rays strikes a crystal and causes the beam of light to spread into many specific directions. From the angles and intensities of these diffracted beams, a crystallographer can produce a...
and published in 1991 by Tom Blundell
Tom Blundell
Sir Tom Leon Blundell, FRS, FMedSci is a British biochemist and science administrator. Up until 2009, he was the Sir William Dunn Professor of Biochemistry and head of the Department of Biochemistry at the University of Cambridge....
in Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
.