Protein Motifs

1-16 Protein Motifs Protein radicals may be defined by their original chronological order or by the arrangement of standby social structure elements The marge motif is delectationd in two different channelise messal in structural biology. The first refers to a separateicular amino-acid age that is feature of speech of a specialized biochemical function. An example is the obscure 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 while motif gradation ligands to a zinc ion whose coordination is essential to energise the tertiary structure. saving is sometimes of a class of residues quite than a specific residue: for example, in the 12-residue loop in the midst of the zinc ligands, ace position is preferentially hydrophobic, specifically leucine or phenylalanine. Sequence motifs can often be recognized by guileless reappr aisal of the amino-acid season of a protein, and when detected extend strong register for biochemical function. The protease from the human immunodeficiency 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 train 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 operative sequence motifs, the former are cognise generally as func tional motifs. An example is the helix-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 ministration 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 outlook 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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