Chapter 4

Chapter 4 - -Large protein molecules often contain more...

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Chapter 4: pages 119-157 -The shape of a protein is specified by its amino acid sequence -Each polypeptide chain consists of a backbone that supports the amino acid side chains, made from the repeating sequence of the core atoms of the amino acids that form the chain. -Noncovalent bonds that help proteins maintain their shape: hydrogen bonds, electrostatic attractions, van der Waals attractions and hydrophobic interaction -In water, nonpolar amino side chains tend to cluster in the interior of the folded protein. -Proteins fold into a conformation of lowest energy -Although protein chains can fold themselves into their correct conformation without outside help, it is generally assisted by molecular chaperones. -Proteins can range in size from about 30 amino acids to 10,000, but most are between 50 and 200. -Alpha helix and beta sheets are common folding patterns, resulting from hydrogen bonds that they form between N-H and C=O groups -2 or 3 a helixes coiled together for a coiled coil -There are only a few functional polypeptide chains
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Unformatted text preview: -Large protein molecules often contain more than one polypeptide chain-Proteins can assemble into filaments, sheets or spheres-Extra cellular proteins are often stabilized by covalent bonds-Most common is the disulfide bond-Anything that binds to a protein is called a ligand-Antibodies, proteins that recognize antigens-Enzymes are proteins-3 ways an enzyme encourage catalysis: binding to two substrate molecules, binding to a substrate and rearranging the electrons, or straining the bound substrate-Feedback inhabitation is negative regulation, preventing an enzyme from acting-Positive regulation stimulates enzyme activity -Many proteins are allosteric , and can adopt 2 or more slightly different conformations-Another method used to regulate protein activity involves attaching a phosphate group to one of the amino acid side chains: phosphorylation-Addition of phosphate catalyzed by protein kinase-Removal of phosphate catalyzed by protein phosphatase...
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Chapter 4 - -Large protein molecules often contain more...

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