Structure of a molecular maquette scaffold.

Format:

Book

Thesis/Dissertation

Author/Creator:

Huang, Steve Shih-Lin.

Contributor:

Dutton, P. Leslie, advisor.

University of Pennsylvania.

Language:

English

Subjects (All):

Biophysics.

0786.

Penn dissertations--Biochemistry and molecular biophysics.

Biochemistry and molecular biophysics--Penn dissertations.

Local Subjects:

Penn dissertations--Biochemistry and molecular biophysics.

Biochemistry and molecular biophysics--Penn dissertations.

0786.

Physical Description:

129 pages

Contained In:

Dissertation Abstracts International 62-11B.

System Details:

Mode of access: World Wide Web.

text file

Summary:

Molecular "maquettes" are small de novo designed polypeptides developed to explore the engineering principles of heme binding proteins. The maquettes consist of alpha helical bundles made of four identical helices. Structural elucidation of maquettes has been complicated by their molten globular nature. A uniquely structured maquette scaffold designed by Gibney et al.[1] allowed for structural elucidation of the apo form by NMR [2] and crystallography. In this work, the crystal structure of BBL31M {sequence: CGGG EIWKL HEEFLKK FEELLKL HEERLKKM} was solved with multiple anomalous diffraction (MAD) experiments. Apo BBL31M is an anti-parallel four-helix bundle with "up-up-down-down" topology. The structure shows unexpected inter-helical crossing angles, residue positioning and translations between the helices. We found that one of the interfaces in BBL31M is packed non-specifically. This may explain the dynamic behavior observed by Skalicky at. al.[2]. The scaffold has no preformed heme binding pocket. The histidine positions indicate that changes in the orientation of helices are necessary for heme binding. The conformational changes may expose hydrophobic residues in the heptad "g"-position and cause the bundles to aggregate upon heme binding. We were able to achieve structural uniqueness in the holo form through a deletion of Arg27 in addition to adjustments of the residue compositions to minimize exterior hydrophobic area. The uniquely structured holo peptide {sequence: CGGG EIWKQ HEEALKK FEEALKQ FEELKKL} is anti-parallel in the two-heme bound state. Both hemes have an identical redox potential of -250mV.

1Gibney, B. R., et al., Design of a unique protein scaffold for maquettes. Journal of the American Chemical Society, 1997. 119(9): p. 2323--2324. 2Skalicky, J. J., et al., Solution structure of a designed four-alpha-helix bundle maquette scaffold. Journal of the American Chemical Society, 199. 121(21): p. 4941--4951.

Notes:

Thesis (Ph.D. in Biochemistry and Molecular Biophysics) -- University of Pennsylvania, 2001.

Source: Dissertation Abstracts International, Volume: 62-11, Section: B, page: 4988.

Adviser: P. Leslie Dutton.

Local Notes:

School code: 0175.

ISBN:

9780493441672

Access Restriction:

Restricted for use by site license.