2pzu
From Proteopedia
Crystal structure of Staphylococcal nuclease variant V66N/P117G/H124L/S128A at cryogenic temperature
Structural highlights
Function[NUC_STAAW] Enzyme that catalyzes the hydrolysis of both DNA and RNA at the 5' position of the phosphodiester bond (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedAlthough internal water molecules are essential for the structure and function of many proteins, the structural and physical factors that govern internal hydration are poorly understood. We have examined the molecular determinants of internal hydration systematically, by solving the crystal structures of variants of staphylococcal nuclease with Gln-66, Asn-66, and Tyr-66 at cryo (100 K) and room (298 K) temperatures, and comparing them with existing cryo and room temperature structures of variants with Glu-66, Asp-66, Lys-66, Glu-92 or Lys-92 obtained under conditions of pH where the internal ionizable groups are in the neutral state. At cryogenic temperatures the polar moieties of all these internal side chains are hydrated except in the cases of Lys-66 and Lys-92. At room temperature the internal water molecules were observed only in variants with Glu-66 and Tyr-66; water molecules in the other variants are probably present but they are disordered and therefore undetectable crystallographically. Each internal water molecule establishes between 3 and 5 hydrogen bonds with the protein or with other internal water molecules. The strength of interactions between internal polar side chains and water molecules seems to decrease from carboxylic acids to amides to amines. Low temperature, low cavity volume, and the presence of oxygen atoms in the cavity increase the positional stability of internal water molecules. This set of structures and the physical insight they contribute into internal hydration will be useful for the development and benchmarking of computational methods for artificial hydration of pockets, cavities, and active sites in proteins. Crystallographic study of hydration of an internal cavity in engineered proteins with buried polar or ionizable groups.,Schlessman JL, Abe C, Gittis A, Karp DA, Dolan MA, Garcia-Moreno E B Biophys J. 2008 Apr 15;94(8):3208-16. Epub 2008 Jan 4. PMID:18178652[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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