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Dissertation Information for Jenna Siracusa Trommel

NAME:
- Jenna Siracusa Trommel

DEGREE:
- Ph.D.

DISCIPLINE:
- Chemistry

SCHOOL:
- Emory University (USA) (2001)

ADVISORS:
- Luigi G. Marzilli

COMMITTEE MEMBERS:
- Karl S. Hagen
- Craig L. Hill

MPACT Status: Fully Complete

Title: Cobalt macrocyclic complexes of biological and potential medical interest

Abstract: "Using EPR and visible spectroscopy, we found that sterically hindered 2-substituted pyridines which bind simple synthetic Co models do not bind Co(II) cobinamide (Co(II)Cbi + ), a B 12 model with the 5,6-dimethylbenzimidazole cofactor loop removed. No adduct (thus, no hyper-long Co(II)-nitrogen axial bond) was formed even by 8 M 2-picoline, if the 2-picoline was purified by a novel Co(III)-affinity distillation procedure to remove trace unhindered nitrogenous impurities. Our results indicate that Co(II)Cbi + selectively binds unhindered sp 2 N-donor ligands, resolving the conflict between EPR experiment and EPR theory.

We prepared two new tetracationic methylcobalt porphyrins ([CH 3 Co(por)] 4+ ), [CH 3 CoTMpyP(4)] 4+ and [CH 3 CoTMAP] 4+ (where [TMpyP(4)] 4+ and [TMAP] 4+ = tetra(N-methyl-4-pyridiniumyl)porphyrin and tetra( N,N,N -trimethylaniliniumyl)porphyrin, respectively), by using the [Co(III)(NH 3 ) 5 CH 3 ] 2+ reagent since reductive alkylation of the electron-poor [Co(II)(por)] 4+ derivatives was difficult. Using viscometric methods, CD, and visible spectroscopy, we determined that both [CH 3 Co(por)] 4+ bind selectively to the outside of AT-rich DNA. Blue-shifts of the [CH 3 Co(por)] 4+ Soret bands upon DNA binding indicate the presence of some of the five-coordinate form, providing the first evidence for five-coordinate CH 3 Co(III)N 4 at equilibrium in water.

Using NMR, visible, and CD spectroscopy, we studied the porphyrin products formed after irradiation of free and DNA-bound [CH 3 Co(por)] 4+ . Ambient irradiation of [CH 3 Co(por)] 4+ in polar aprotic solvents yielded [CH 3 OOCo(por)] 4+ . Ambient irradiation of [CH 3 CoTMAp] 4+ bound to CT DNA or to [poly(dA-dT)] 2 gave a larger amount of DNA-bound [Co(II)TMAP] 4+ than observed with [poly(dG-dC)] 2 , demonstrating that [Co(II)TMAP] 4+ binds selectively to AT-rich DNA. The intense conservative induced CD signal of DNA-bound [Co(II)TMAP] 4+ suggested that the cation binds to the outside of DNA with a high degree of self-stacking."

MPACT Scores for Jenna Siracusa Trommel

A = 0
C = 0
A+C = 0
T = 0
G = 0
W = 0
TD = 0
TA = 0
calculated 2008-04-07 07:47:34

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