Cavities of alpha(1)-antitrypsin that play structural and functional roles

Lee, C Maeng, JS Kocher, JP Lee, B Yu, MH

C. Lee et al., Cavities of alpha(1)-antitrypsin that play structural and functional roles, PROTEIN SCI, 10(7), 2001, pp. 1446-1453

42

INGLESE

Article

Biochemistry & Biophysics

PROTEIN SCIENCE

0961-8368 → ACNP

10

7

2001

1446 - 1453

ISI

0961-8368(200107)10:7<1446:COATPS>2.0.ZU;2-7

The native form of inhibitory serine protease inhibitors (serpins) is strai ned, which is critical for their inhibitory activity. Previous studies on s tabilizing mutations of alpha (1)-antitrypsin, a prototype of serpins, indi cated that cavities provide a structural basis for the native strain of the molecule. We have systematically mapped the cavities of alpha (1)-antitryp sin that play such structural and functional roles by designing cavity-fill ing mutations at residues that line the walls of the cavities, Results show that energetically unfavorable cavities are distributed throughout the alp ha (1)-antitrypsin molecule, and the cavity-filling mutations stabilized th e 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 dep end largely on the structural flexibility of the cavity environment. Cavity -filling mutations that decreased inhibitory activity of alpha (1)-antitryp sin were localized in the loop regions that interact with beta -sheet A dis tal from the reactive center loop. The results are consistent with the noti on that beta -sheet A and the structure around it mobilize when alpha (1)-a ntitrypsin forms a complex with a target protease.