title: Cavities of alpha(1)-antitrypsin that play structural and functional roles.
abstract: The native form of inhibitory serine protease inhibitors (serpins) is strained, which is critical for their inhibitory activity. Previous studies on stabilizing mutations of alpha(1)-antitrypsin, a prototype of serpins, indicated that cavities provide a structural basis for the native strain of the molecule. We have systematically mapped the cavities of alpha(1)-antitrypsin that play such structural and functional roles by designing cavity-filling mutations at residues that line the walls of the cavities. Results show that energetically unfavorable cavities are distributed throughout the alpha(1)-antitrypsin molecule, and the cavity-filling mutations stabilized the native conformation at 8 out of 10 target sites. The stabilization effect of the individual cavity-filling mutations of alpha(1)-antitrypsin varied (0.2-1.9 kcal/mol for each additional methylene group) and appeared to depend largely on the structural flexibility of the cavity environment. Cavity-filling mutations that decreased inhibitory activity of alpha(1)-antitrypsin were localized in the loop regions that interact with beta-sheet A distal from the reactive center loop. The results are consistent with the notion that beta-sheet A and the structure around it mobilize when alpha(1)-antitrypsin forms a complex with a target protease.
authors: National Creative Research Initiatives, Protein Strain Research Center, Korea Institute of Science and Technology, Cheongryang, Seoul 130-650, Korea.
authors: C
authors: C
authors: Lee
authors: J S
authors: JS
authors: Maeng
authors: J P
authors: JP
authors: Kocher
authors: B
authors: B
authors: Lee
authors: M H
authors: MH
authors: Yu
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D004355:Drug Stability; D019791:Guanidine / Q000494:pharmacology; D016297:Mutagenesis, Site-Directed; D010196:Pancreatic Elastase / Q000037:antagonists & inhibitors / Q000378:metabolism; D011489:Protein Denaturation / Q000187:drug effects; D017434:Protein Structure, Tertiary; D013552:Swine; D000515:alpha 1-Antitrypsin / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*
chemical_list: D000515:alpha 1-Antitrypsin; D010196:Pancreatic Elastase; D019791:Guanidine