The aim in the proposed research is to determine the three- dimensional structure (by x-ray diffraction of single crystals) of a number of peptides (10-30 residues) that perform a variety of functions such as ion transport, analgesia, toxic, antitoxic, and antibiotic by means of single crystal x-ray diffraction analysis. These crystals are composed of molecules containing light atoms only, C, N, O and H. The method of solution will be direct phase determination using the tangent formula and a variety of auxiliary formulas. Linear peptides mediating ion transport through cell membranes, particularly those in the class of peptaibophol antibiotics, are being emphasized currently. They are characterized by their length (up to 20 residues), a number of Aib residues (alpha aminoisobutyric acid) and one or more Pro residues that interfere with alpha-helix formation. The immediate goal is to establish the conformation of neighboring peptide molecules in the crystal. The ultimate goal is to determine modes of aggregation that form ion channels in membranes. The specific peptide structures that are being studied and will continue to be studied are polymorphs of 10-residue apolar analogs of zervamicin II; the 16-residue antiamoebin; Boc(Aib- Ala-Leu)3-Aib-OMe, a 10-residue fragment of an ion transport peptide; Boc-Cys-Val-Aib-Ala-Leu-Cys-NHMe; and others, including the continuation of structure analyses of gramicidin A, a dodecapeptide from elastin, and a new conformation for uncomplexed valinomycin from a very polar solvent.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM030902-08
Application #
3278781
Study Section
Biophysics and Biophysical Chemistry A Study Section (BBCA)
Project Start
1982-08-01
Project End
1993-07-31
Budget Start
1989-08-01
Budget End
1990-07-31
Support Year
8
Fiscal Year
1989
Total Cost
Indirect Cost
Name
U.S. Naval Research Laboratory
Department
Type
DUNS #
020060658
City
Washington
State
DC
Country
United States
Zip Code
20375
Karle, Isabella L; Huang, Lulu; Venkateshwarlu, Punna et al. (2009) SUBTLE CONTROL IN SOLUTION AND CRYSTAL STRUCTURES WITH WEAK HYDROGEN BONDS: THE UNUSUAL PROFILE OF DIMETHYL 3, 12-DIOXO-7, 8 DITHIA 4, 11-DIAZABICYCLO[12.2.2]OCTADECA-1(16), 14, 17-TRIENE 5, 10-DICARBOXYLATE (TDA1). Heterocycles 79:471-486
Huang, Lulu; Massa, Lou; Karle, Isabella et al. (2009) Calculation of strong and weak interactions in TDA1 and RangDP52 by the kernel energy method. Proc Natl Acad Sci U S A 106:3664-9
Karle, Isabella L; Ranganathan, Darshan; Kumar, Mittapalli Gopi et al. (2008) Design, synthesis, conformational and membrane ion transport studies of proline-adamantane hybrid cyclic depsipeptides. Biopolymers 89:471-8
Karle, Isabella L; Venkateshwarlu, Punna; Nagaraj, Ramakrishnan et al. (2007) Diphenic acid as a general conformational lock in the design of bihelical structures. Chemistry 13:4253-63
Karle, Isabella L; Venkateshwarlu, P; Ranganathan, S (2006) A robust hybrid peptide crystal formed with weak hydrogen bonds. Biopolymers 84:502-7
Roy, Rituparna S; Gopi, Hosahudya N; Raghothama, Srinivasarao et al. (2006) Hybrid peptide hairpins containing alpha- and omega-amino acids: conformational analysis of decapeptides with unsubstituted beta-, gamma-, and delta-residues at positions 3 and 8. Chemistry 12:3295-302
Karle, I L; Ranganathan, D (2005) An asymmetric conformation of 1,3,5-benzene tricarbonyl [Aib4OMe]3. J Pept Res 65:65-70
Roy, Rituparna S; Gopi, Hosahudya N; Raghothama, S et al. (2005) Peptide hairpins with strand segments containing alpha- and beta-amino acid residues: cross-strand aromatic interactions of facing Phe residues. Biopolymers 80:787-99
Roy, Rituparna S; Karle, Isabella L; Raghothama, S et al. (2004) Alpha,beta hybrid peptides: a polypeptide helix with a central segment containing two consecutive beta-amino acid residues. Proc Natl Acad Sci U S A 101:16478-82
Karle, I L; Prasad, S; Balaram, P (2004) A combined extended and helical backbone for Boc-(Ala-Leu-Ac7c-)2-OMe. J Pept Res 63:175-80

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