PMID- 18208453
OWN - NLM
STAT- MEDLINE
DCOM- 20080911
LR  - 20211203
IS  - 0031-8655 (Print)
IS  - 0031-8655 (Linking)
VI  - 84
IP  - 3
DP  - 2008 May-Jun
TI  - Effect of dimerization on vibrational spectra of eumelanin precursors.
PG  - 613-9
LID - 10.1111/j.1751-1097.2007.00273.x [doi]
AB  - We have synthesized a compound ideally suited to the study of structure-function 
      relationships in eumelanin synthesis. N-methyl-5-hydroxy-6-methoxy-indole (MHMI) 
      has key functional groups strategically placed on the indole framework to hinder 
      binding in the 2, 5, 6 and 7 positions. Thus, the dimer bound exclusively in the 
      4-4' positions was isolated and characterized. In order to study the difference 
      in vibrational structure between the MHMI monomer and dimer, Raman spectra were 
      acquired of both compounds, as well as indole, indole-2-carboxylic acid and 
      5,6-dihydroxyindole-2-carboxylic acid (DHICA). Peaks were assigned to particular 
      vibrational modes using B3LYP density functional theory calculations, and 
      experimental and theoretical spectra displayed good agreement. Addition of 
      functional groups to either benzene or pyrrole rings in the indole framework 
      impacted vibrational spectra attributed to vibrations in either ring, and in some 
      cases, peaks appearing unchanged between two compounds corresponded to different 
      contributing vibrations. Dimerization resulted in an expected increase in the 
      number of vibrational modes, but not a significant increase in the number of 
      apparent peaks, as several modes frequently contributed to an individual observed 
      peak. Comparison of spectral features of the monomer and dimer provides insight 
      into eumelanin photochemistry, but final conclusions depend on the planarity of 
      oligomeric structure in vivo.
FAU - Nighswander-Rempel, Stephen P
AU  - Nighswander-Rempel SP
AD  - Centre for Biophotonics and Laser Science, School of Physical Sciences, 
      University of Queensland, Brisbane, Queensland, Australia. 
      snighrem@physics.uq.edu.au
FAU - Olsen, Seth
AU  - Olsen S
FAU - Mahadevan, Indumathy B
AU  - Mahadevan IB
FAU - Netchev, George
AU  - Netchev G
FAU - Wilson, Brian C
AU  - Wilson BC
FAU - Smith, Sean C
AU  - Smith SC
FAU - Rubinsztein-Dunlop, Halina
AU  - Rubinsztein-Dunlop H
FAU - Meredith, Paul
AU  - Meredith P
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20080115
PL  - United States
TA  - Photochem Photobiol
JT  - Photochemistry and photobiology
JID - 0376425
RN  - 0 (Carboxylic Acids)
RN  - 0 (Indoles)
RN  - 0 (Melanins)
RN  - 12627-86-0 (eumelanin)
RN  - 1477-50-5 (indole-2-carboxylic acid)
RN  - 4790-08-3 (5,6-dihydroxy-2-indolylcarboxylic acid)
SB  - IM
MH  - Carboxylic Acids
MH  - Dimerization
MH  - Indoles/*chemistry
MH  - Melanins/*chemical synthesis/*chemistry
MH  - Spectrophotometry, Infrared
MH  - Spectrum Analysis, Raman
MH  - Structure-Activity Relationship
MH  - Vibration
EDAT- 2008/01/23 09:00
MHDA- 2008/09/13 09:00
CRDT- 2008/01/23 09:00
PHST- 2008/01/23 09:00 [pubmed]
PHST- 2008/09/13 09:00 [medline]
PHST- 2008/01/23 09:00 [entrez]
AID - PHP273 [pii]
AID - 10.1111/j.1751-1097.2007.00273.x [doi]
PST - ppublish
SO  - Photochem Photobiol. 2008 May-Jun;84(3):613-9. doi: 
      10.1111/j.1751-1097.2007.00273.x. Epub 2008 Jan 15.