title: Structural engineering of the HIV-1 protease molecule with a beta-turn mimic of fixed geometry.
abstract: An important goal in the de novo design of enzymes is the control of molecular geometry. To this end, an analog of the protease from human immunodeficiency virus 1 (HIV-1 protease) was prepared by total chemical synthesis, containing a constrained, nonpeptidic type II' beta-turn mimic of predetermined three-dimensional structure. The mimic beta-turn replaced residues Gly16,17 in each subunit of the homodimeric molecule. These residues constitute the central amino acids of two symmetry-related type I' beta-turns in the native, unliganded enzyme. The beta-turn mimic-containing enzyme analog was fully active, possessed the same substrate specificity as the Gly16,17-containing enzyme, and showed enhanced resistance to thermal inactivation. These results indicate that the precise geometry of the beta-turn at residues 15-18 in each subunit is not critical for activity, and that replacement of the native sequence with a rigid beta-turn mimic can lead to enhanced protein stability. Finally, the successful incorporation of a fixed element of secondary structure illustrates the potential of a "molecular kit set" approach to protein design and synthesis.
authors.affiliation: Scripps Research Institute, La Jolla, California 92037.
authors.forename: M
authors.initials: M
authors.lastname: Baca
authors.forename: P F
authors.initials: PF
authors.lastname: Alewood
authors.forename: S B
authors.initials: SB
authors.lastname: Kent
mesh_terms: D000595:Amino Acid Sequence; D003545:Cysteine / Q000031:analogs & derivatives; D004151:Dipeptides / Q000737:chemistry; D004795:Enzyme Stability; D016333:HIV Protease / Q000737:chemistry* / Q000378:metabolism; D006358:Hot Temperature; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000737:chemistry; D015202:Protein Engineering; D017433:Protein Structure, Secondary; D013379:Substrate Specificity
chemical_list: D004151:Dipeptides; D010456:Peptides, Cyclic; C082915:2-oxo-3-tert-butyloxycarbonylamino-7-thia-1-azabicyclo(4.3.0)nonane-9-carboxylic acid; D016333:HIV Protease; D003545:Cysteine