Protein Motifs

1-16 Protein Motifs Protein radicals may be defined by their ancient chronological order or by the arrangement of standby construction elements The marge motif is delectationd in two different enthrall messal in structural biology. The first refers to a divideicular amino-acid installment that is peculiarity of a specialized biochemical function. An example is the debatable 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 epoch motif gradation ligands to a zinc ion whose coordination is essential to becalm the tertiary structure. saving is sometimes of a class of residues quite a than a specific residue: for example, in the 12-residue loop betwixt the zinc ligands, ace position is preferentially hydrophobic, specifically leucine or phenylalanine. Sequence motifs can often be recognized by plain reappraisal of the ami no-acid sequence of a protein, and when detected admit 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 laid 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 functional sequence motifs, the former are cognise generally as functional motifs. An example is the helix-turn-helix m! otif 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 rest period 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 campaigner 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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