title: Effect of a specific hydrogen bond (N138ND2-Q106O) on conformational integrity, stability, and activity of staphylococcal nuclease.
abstract: There are two hydrogen bonding interactions (N138ND2-Q106O and Y54OH-S141OG) between the C-terminal region and the main body of staphylococcal nuclease (SNase). To examine the role of these hydrogen bonds, SNase(141) and its three mutants, SNase(141)N138D, SNase(141)S141A, and SNase(141)N138D/S141A, were created. The N138D mutation has the N138ND2-Q106O interaction deleted and the S141A mutation has the Y54OH-S141OG and S141OG-N138O interactions deleted. The conformational features, stability, and activity of the proteins have been compared by using circular dichroism, intrinsic and ANS-binding fluorescence, GdnHCl-induced denaturation, and activity assay. The results clearly show that the N138D mutation significantly alters the secondary and tertiary structures of the protein, producing a partially unfolding state; in contrast, the S141A mutation has no such effect on structure. These results strongly suggest that the specific hydrogen bond, N138ND2-Q106O, plays an important role in maintaining the conformational integrity and stability of the nuclease.
authors: National Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica, Beijing 100101, PR China.
authors: Sun
authors: S
authors: Huang
authors: Jinhu
authors: J
authors: Yin
authors: Yanming
authors: Y
authors: Feng
authors: Guozhong
authors: G
authors: Jing
mesh_terms: D004789:Enzyme Activation; D004795:Enzyme Stability; D006860:Hydrogen Bonding; D008836:Micrococcal Nuclease / Q000737:chemistry* / Q000378:metabolism*; D009154:Mutation; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry* / Q000378:metabolism; D013210:Staphylococcus / Q000737:chemistry / Q000201:enzymology; D013329:Structure-Activity Relationship
chemical_list: D011994:Recombinant Proteins; D008836:Micrococcal Nuclease