Protein! s properties

A pure preparation is essential before a protein s properties and activities can be determined. Given that cells contain thousands of different kinds of proteins, how can one protein be purified Methods for separating proteins take advantage of properties that vary from one protein to the next, including size, charge, and binding properties. 

Even when an enzyme is studied exhaustively, identifying the amino acid residues that control the catalytic activity is a difficult task In fact, site-specific single mutations rarely do their job, since single mutations far from the active site can change the protein s properties. 

Each amino acid has a different R group, or side chain. The side chains of the amino acids in a protein determine the protein s properties. In Table 25.2 the side chains of the amino acids are shown within a color screen. Nine of the amino acids have nonpolar, or hydrocarbon, side chains (left side of table). The remaining 11 amino acids have polar side chains (right side of table), capable of ionizing or forming hydrogen bonds with other amino acids or with water. 

John.son, L. N., and Barford, D., 1994. Electro.static effects in die control of glycogen pho.sphoryla.se by pho.sphorylation. Protein Science 3 1726-1730. Di.scn.s.sion of die pho.sphate group s ability to deliver two negative charges to a protein, a property that no amino acid side chain can provide. 

Precisely defined collections of different chemical compounds are denominated as chemical libraries that can be efficiently prepared by methods of combinatorial chemistry. Each chemical compound owes specific structural, steiic, and electronic properties that determine all possible interactions of the small molecule with a given protein or receptor. The molecule s properties are based on the steiic arrangement of functional groups, including the conformations that can be attained by a specific structure. 

Yu, M., Goldberg, S., Goldberg, A.L. (1W2). Heat shock in Escherichia coli alters the protein-binding properties of the chaperonin groEL by inducing its phosphorylation. Nature 357, 167-169. 

Patel S, Mackerell AD, Brooks CL (2004) CHARMM fluctuating charge force field for proteins II -Protein/solvent properties from molecular dynamics simulations using a nonadditive electrostatic model. J Comput Chem 25(12) 1504-1514... 

The distinguishing structural and functional protein for caveolae is caveolin. Caveolin proteins display properties that are likely involved in the distinguishing morphology of caveolae. Caveolins have a high affinity for both cholesterol and sphingolipids coupled with 3 carboxy-terminal palmitoylated cysteine residues. Three isoforms of caveolin exist and show distinct tissue distribution. Likely because it was discovered first and is perhaps most abundant, caveolin-1 has garnered the lion s share of research attention. 

Characterization Characterizing the Protein s Physical-Chemical and Biological Properties... 

Several features affect the rate of amide hydrogen exchange, which reflect the protein s structure and dynamic properties. These include an amide s participation in hydrogen bonding [36], its distance from the protein surface [3], and the... 

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