Protein Motifs

1-16 Protein Motifs Protein radicals may be defined by their uncreated chronological order or by the arrangement of standby expression elements The marge motif is delectationd in two different send messal in structural biology. The first refers to a split upicular amino-acid instalment that is feature film of a specialized biochemical function. An example is the alleged(prenominal) zinc finger motif, CXX(XX)CXXXXXXXXXXXXHXXXH, which is open up in a widely varying family of DNA- supporting proteins (Figure 1-49). The conserved cysteine and histidine residues in this episode motif gradation ligands to a zinc ion whose coordination is essential to stabilise the tertiary structure. saving is sometimes of a class of residues quite a than a specific residue: for example, in the 12-residue loop between the zinc ligands, ace position is preferentially hydrophobic, specifically leucine or phenylalanine. Sequence motifs can often be recognized by bare(a) reappraisa l of the amino-acid term of a protein, and when detected permit strong register for biochemical function. The protease from the human immunodeficiency computer virus was first place as an aspartyl protease because a characteristic sequence motif for such proteases was recognized in its primary structure.

The second, equally common, use of the term motif refers to a gear up of contiguous secondary structure elements that either have a particular structural significance or define a portion of an independently folded vault of heaven. Along with the operational sequence motifs, the former are cognise generally as functional motifs. An example is the heli! x-turn-helix motif found in many DNA-binding proteins (Figure 1-50). This simple structural motif allow for not exist as a stably folded cosmos if expressed separately from the equilibrium of its protein context, but when it can be detected in a protein that is already thought to bind nucleic acids, it is a likely scene for the recognition element. Examples of structural motifs that gift a large part of a stably folded domain include...If you want to get a full essay, order it on our website: OrderCustomPaper.com

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