OXIDATION OF TETRAPEPTIDES OF ELASTIN SEQUENCES WITH MN(III)
47
Amis [32] has shown that plots of log kobs vs. 1/D
give a straight line with a positive slope for positive
ion-dipole interaction. The positive dielectric effect in
the present investigation shows charge dispersal in the
transition state, pointing towards a positive ion-dipole
reaction and hence supports Scheme II.
7. Rangappa, K. S.; Chandraju, S.; Made Gowda, N. M. Int
J Chem Kinet 1998, 30, 7.
8. Rangappa, K. S.; Manjunathaswamy, H.; Ragavendra,
M. P.; Channe Gowda, D. Carbohydr Res 1998, 307,
253.
9. Rangappa, K. S.; Manjunathaswamy, H.; Ragavendra,
M. P.; Channe Gowda, D. J Org Chem 1998, 63, 531.
10. Rangappa, K. S.; Ragavendra, M. P.; Mahadevappa,
D. S. Carbohydr Chem 1997, 16, 359.
11. Mahadevappa, D. S.; Ananda, S.; Made Gowda, N. M.;
Rangappa, K. S. J Chem Soc Perkin Trans II, 1985, 11,
39.
12. Rangappa, K. S.; Chandaraju, S.; Mahadevappa, D. S.
Transition Met Chem 1996, 21, 519.
13. Asha Iyengar, T.; Mahadevappa, D. S. Indian J Chem
1992, 31A, 752.
14. Sandberg, L. B.; Leslie, J. G.; Leach, C. T.; Torres,
V. L.; Smith, A. R.; Smith, D. W. Pathol Biol 1985,
33, 266.
15. Yeh, H.; Ornstein-Goldstein, N.; Indik, Z.; Sheppard, P.;
Anderson, N.; Rosenbloom, J. C.; Cicila, G.; Yoon, K.;
Rosenbloom, J. Collagen Relat Res 1987, 7, 235.
16. Sandberg, L. B.; Soskel, N. T.; Leslie, J. B. Engl J Med
1981, 304, 566.
The rate of oxidation of TETP by Mn(III) was com-
pared with that of oxidation of tripeptides, Gly-Ala-
Pro, Gly-Ile-Pro and Gly-Phe-Pro, dipeptides, Ala-
Pro, Ile-Pro and Phe-Pro, and free amino acids by
Mn(III) under identical experimental conditions, and
it was found that the rate of oxidation of tetrapep-
tide was slower than either tripeptides, dipeptides, and
free amino acids. The change in each case is due to
the increased distance between the functional groups
and consequently weaker electrostatic effects. Hence,
the oxidation of the tetrapeptides is expected to be
slower than the monomers, dipeptides, and tripep-
tides. Further, an apparent correlation was noted be-
tween the rate of oxidation and the hydrophobicity
of these sequences, where increased hydrophobicity
results in increased rate of oxidation. The order of
rate of oxidation of tetrapeptides was found to be
GGFP > GGIP > GGAP which is well in agreement
with their hydrophobicity [33].
17. Urry, D. W.; Long, M. M. CRC Crit Rev Biochem 1976,
4, 1.
18. Urry, D. W.; McKee, L. D.; Williams, T.; Olsen, D. B.;
Cox, B. A. Medical Application of Bioelastic Materials,
in Biotechnological Polymers: Medical, Pharmaceuti-
cal and Industrial Applications, Technomic Publishing:
Atlanta, Georgia, 1993; pp. 82.
19. Urry, D. W.; McPherson, D. T.; Xu, J.; Daniell, H.;
Guda, C.; Channe Gowda, D.; Jing, N.; Parker, T.
M. Polymeric Materials Encyclopedia, Salamone, J. C.
(Ed.); CRC Press: Boca Raton, 1996; pp. 7263.
20. Nicol, A.; Channe Gowda, D.; Parker, T. M.; Urry, D. W.
J Biomed Mater Res 1993, Vol. 27, pp. 801.
21. Anwer, M. K.; Spatola, A. F. Synthesis 1980, 929.
Spectral Evidence for the Formation
of TETP–Mn (III) Complex
The study of UV–Visible spectra separately of
pure Mn(III), TETP (glycyl-glycyl-alanyl-proline,
glycyl-glycyl-phenylalanyl-proline,
and
glycyl-
glycyl-isoleucyl-proline), and a mixture of Mn(III)
and TETP show deviation in peak wave length(
and absorbance(Abs) as follows.
)
max
Substrate
in nm
Abs
Complex
in nm
max
Abs
max
Mn(III)
GGAP
GGIP
500
0.970
2.789
3.000
2.913
215.0
223.0
222.0
Mn(III) + GGAP
Mn(III) + GGIP
Mn(III) + GGFP
241.5
238.5
239.5
2.987
3.063
3.023
GGFP
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