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Dissertation Information for Manuela Trani

NAME:
- Manuela Trani

DEGREE:
- Ph.D.

DISCIPLINE:
- Chemistry

SCHOOL:
- Emory University (USA) (2006)

ADVISORS:
- Dale E. Edmondson

COMMITTEE MEMBERS:
- Karl S. Hagen
- Kurt Warncke

MPACT Status: Fully Complete

Title: Chemical studies of molybdenum and of platinum in biological systems: Role of molybdenum in biological hydroxylations and anticancer activities of platinum complexes

Abstract: The role of molybdenum in biological hydroxylations is addressed by studies of recombinant Comamonas acidovorans Xanthine Dehydrogenase (XDH). Highly functional (>90%) C. acidovorans XDH is heterologously expressed in high level in P. aeruginosa . Coexpression of P. aeruginosa xdhC in stoichiometric levels is required for maximal level of Mo incorporation and for high level of functional expression of XDH . XdhC -catalyzed Mo incorporation is decreased by the presence of tungsten in the expression media, resulting in the formation of demolybdo XDH. Tungsten is proposed to prevent Mo insertion by inhibiting the function of XDHC. Glu277Gln and Glu758Gln XDH mutants are expressed from P. aeruginosa and purified. Compared to WT enzyme (100%), catalytic activities measured for Glu277Gln and Glu758Gln mutants are only ¡­2% and ¡­0.2%, respectively. Wild-type, Glu277Gln, and Glu758Gln C. acidovorans XDH exhibit small substrate deuterium isotope effects of 1.5 in the 4.5-9.5 pH range. The pH dependence of kinetic parameters exhibit two ionizations important for catalysis for wild-type (pK a1 = 7.2, pK a2 = 8.7); Glu277Gln (pK a1 = 5.8, pK a2 = 8.9) and single ionization for Glu758Gln (pK a2 = 9.2). These results unequivocally assign Glu758 as the active site base proposed to be crucial in the XDH catalytic mechanism. Cis -PtA 2 (Me 2 Bzm) 2 complexes (A 2 = 2,2'-bipiperidine (Bip) and N,N,N',N' -tetramethyl-2,3-diaminobutane (Me 4 DAB); Me 2 Bzm = 5,6-dimethylbenzimidazole), modeling the cisplatin-DNA cross-link, are investigated by NMR. In cis -PtA 2 B 2 adducts (B = guanine or Me 2 Bzm base), interconversion among the possible rotamers, one head-to-head (HH) and two head-to-tail (HT), by rotation about the Pt-N7 bond of guanine or the Pt-N3 bond of Me 2 Bzm is slow on the NMR time scale. The amounts of the rarely observed HH conformer were 52 and 37% at 5¡ÆC for BipPt(Me 2 Bzm) 2 and Me 4 DABPt(Me 2 Bzm) 2 , respectively. This result represents the first reported clear evidence for the existence of the HH atropisomer in cis -PtA 2 B 2 adducts with fully substituted diamines, and demonstrates that the lack of an O-substituent on the C4 atom of Me 2 Bzm (corresponding to C6 of guanine) allows for a relatively stable HH conformer.

MPACT Scores for Manuela Trani

A = 0
C = 0
A+C = 0
T = 0
G = 0
W = 0
TD = 0
TA = 0
calculated 2008-02-03 19:49:59

Advisors and Advisees Graph