This may include bundles of helices, beta strands stacked side-by-side into beta sheets that are then sandwiched together, and numerous other combinations. The whole chain, with all of these local secondary structures, is then folded into the overall tertiary structure of the protein chain. Other specialized secondary structures are also observed, including defined structures for small loops and other types of helices. Both of these secondary structures arrange the chain so that most of the main chain atoms form hydrogen bonds with themselves in a very efficient way (Figure 2)-alpha helices form hydrogen bonds within the helix, and beta strands form hydrogen bonds with neighboring strands when arranged into beta sheets. There are two common secondary structures: alpha helices and beta strands. Nearly all folded proteins have structural elements that are formed in local regions of the protein chain. In all living cells, this order is encoded in the organism's genome, and the protein is built by ribosomes by connecting amino acids in the proper order. This is the ordering of amino acids in the protein chain. Protein structure is usually broken down into four hierarchical levels of organization (Figure 1): By understanding the way the proteinĬhain folds into this functional structure, researchers are now beginning to be able to predict the structure ofĪny protein, as with the recent successes in AlphaFold2 and RoseTTAFold,Īnd also to design proteins with new functions. For example, enzymes have a structure that creates a pocket thatĪrranges reactive amino acids in perfect orientations to perform a chemical reaction. The structure of a protein is central to its function. Why is Understanding Protein Folding Important? Proteins" and are typically not subject to the structural hierarchy described here. These are termed "intrinsically disordered Please note that many cellular proteins have portions that do not adopt a defined, folded structure as part of theirįunction, or only adopt a defined structure when they bind to other proteins. Ranked levels, where simpler levels are arranged into more complex levels. The term "hierarchy" refers to something that is made of
One of the centralĭiscoveries is that proteins have a hierarchical structure. The structure of myoglobin revealed this for the first time, and since then, many of theįeatures of folded proteins have been revealed as more and more structures have been determined. One of the earliest insights from structural biology was that many of the protein chains in cells fold into definedģ-dimensional structures. Diversity, Equity, Inclusion, and Access.Exploring the Structural Biology of Bioenergy.
Exploring the Structural Biology of Cancer.
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