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(The tertiary structure of a protein consists of the way a polypeptide is formed of a complex molecular shape. This is caused by R-group interactions such as ionic and hydrogen bonds, disulphide bridges, and hydrophobic & hydrophilic interactions. Protein tertiary structure is the three-dimensional shape of a protein.
The sequence of the tetraloop and its receptor often covary so that the same type of tertiary contact can be made with different isoforms of the tetraloop and its cognate receptor. [41] For example, the self-splicing group I intron relies on tetraloop receptor motifs for its structure and function.
Lipocalins are typically eight-stranded up-and-down beta barrel proteins that are secreted into the extracellular environment. A distinctive feature is their ability to bind and transport small hydrophobic molecules in the barrel calyx. Examples of the family include retinol binding proteins (RBPs) and major urinary proteins (Mups).
Secondary and tertiary structure of the coiled-coil motif. The heptad repeat often consists of specific amino acids, seen in the figure. Knobs into packing is also shown. [27] The general problem of deciding on the folded structure of a protein when given the amino acid sequence (the so-called protein folding problem) has only been solved ...
Numerous protein structures are the result of rational design and do not exist in nature. Proteins can be designed from scratch (de novo design) or by making calculated variations on a known protein structure and its sequence (known as protein redesign). Rational protein design approaches make protein-sequence predictions that will fold to ...
A hairpin is a special case of a turn, in which the direction of the protein backbone reverses and the flanking secondary structure elements interact. For example, a beta hairpin connects two hydrogen-bonded , antiparallel β-strands (a rather confusing name, since a β-hairpin may contain many types of turns – α, β, γ, etc.).
For example, the RNA component of the human telomerase contains a pseudoknot that is critical for its activity. [7] The hepatitis delta virus ribozyme is a well known example of a catalytic RNA with a pseudoknot in its active site. [10] [11] Though DNA can also form pseudoknots, they are generally not present in standard physiological conditions.
This E-box consists of the DNA sequence CANNTG, where N can be any nucleotide. [7] 1994: Harrison's [12] and Pabo's [13] groups crystallize bHLH proteins bound to E-boxes, demonstrating that the parallel 4-helix bundle motif loop orients the basic sequences to interact with specific nucleotides in the major groove of the E-box.