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12 terms

Protein structure

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Alpha helix
A common motif in the secondary structure of proteins in which every backbone N-H group donates a hydrogen bond to the backbone C=O group of the amino acid four residues earlier (i+4 \rightarrow i hydrogen bonding). This secondary structure is also sometimes called a classic Pauling-Corey-Branson alpha helix
Beta sheet
the second form of regular secondary structure in proteins consist of beta strands connected laterally by at least two or three backbone hydrogen bonds, forming a generally twisted, pleated sheet. A beta strand (also β strand) is a stretch of polypeptide chain typically 3 to 10 amino acids long with backbone in an almost fully extended conformation. The higher-level association of β sheets has been implicated in formation of the protein aggregates and fibrils observed in many human diseases
Secondary structure
regularly repeating local structures stabilized by hydrogen bonds. The most common examples are the alpha helix, beta sheet and turns. Because secondary structures are local, many regions of different secondary structure can be present in the same protein molecule.
Turn
an element of secondary structure in proteins where the polipeptide chain reverses its overall direction
Tertiary structure
the overall shape of a single protein molecule; the spatial relationship of the secondary structures to one another. he tertiary structure is what controls the basic function of the protein.
Salt bridge
a combination of two noncovalent interactions: hydrogen bonding and electrostatic interactions. This is most commonly observed to contribute stability to the entropically unfavorable folded conformation of proteins. known to be fairly weak interactions, small stabilizing interactions can add up to make an important contribution to the overall stability of a protien
what stabilizes the tertiary structure of a protien?
most commonly the formation of a hydrophobic core, but also through salt bridges, hydrogen bonds, disulfide bonds, and even post-translational modifications.
Quaternary structure
the structure formed by several protein molecules (polypeptide chains)
what are the three main protien structures?
globular proteins, fibrous proteins, and membrane proteins
Globular proteins
one of the two main protein classes, comprising "globe"-like proteins that are more or less soluble in aqueous solutions (where they form colloidal solutions)
Scleroproteins, or fibrous proteins
The roles of such proteins include protection and support,[2] forming connective tissue, tendons, bone matrices, and muscle fiber. are structural proteins or storage proteins that are typically inert and water-insoluble. occurs as an aggregate due to hydrophobic side chains that protrude from the molecule. tend not to denature as easily as globular proteins
membrane protein
a protein molecule that is attached to, or associated with the membrane of a cell or an organelle. More than half of all proteins interact with membranes.