Environmental Engineering Reference
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Yamashita and Jaffé 2008 ). The molecular formula of tryptophan is C 11 H 12 N 2 O 2
and its molecular weight is 204.23. The chemical structure of tryptophan,
C 8 H 5 (NH)-CH 2 (NH 3
)CHCOO , is relatively simple (Fig. 3 q). The fluorophore
at peak T is probably linked to the functional group, -CH 2 -(NH 3
+
)-CH-COO ,
while the fluorophore at peak T uv is probably connected to the C 8 H 5 (NH)- group
that contains the aromatic ring (Mostofa et al. 2009a ). The resonance configuration
of the functional group, -CH 2 -(NH 3
+
)-CH-COO (Fig. 3 r), may confirm the peak
position of the T-region at longer wavelengths than the T UV T-region The fluores-
cence intensity of tryptophan at peak T uv is much stronger (two to threefold higher)
than that of peak T. It might be a useful indicator to differentiate the tryptophan-like
component from the protein-like component, which typically shows higher fluores-
cence at the peak T-region than at the peak T UV -region (Fig. 3 m, n). Tryptophan
is derived microbially from algae, phytoplankton and bacteria in freshwater,
marine and sediment pore waters (Chen and Bada 1989 ; Coble 1996 ; Yamashita
and Tanoue 2003a ; Mostofa et al. 2005b ; Determann et al. 1998 ; Baek et al. 1988 ;
Petersen 1989 ; Wu and Tanoue 2001b ; Wu et al. 2001 ; Cammack et al. 2004 ). Its
very intense fluorescence in aqueous solution could be connected to the functional
group -CH 2 -(NH 3
+
)-CH-COO (Fig. 3 r). Tryptophan is decomposed both pho-
tolytically and microbially in natural waters (Mostofa et al. 2010 , 2007a ; Winter et
al. 2007 ; Moran et al. 2000 ). The fluorescence Ex/Em wavelength maxima of tryp-
tophan mostly depend on the polarity of the solvent and the type of the protein. The
fluorescence of protein-bound tryptophan is in fact shifted to shorter wavelengths
due to shielding from water (Lakowicz 1983 ; Wolfbeis 1985 ).
The tyrosine-like component can exhibit two fluorescence peaks at Ex/
Em = 270-280/293-314 nm in the peak T-region and at 230/304-307 nm in the
peak T UV -region (Fig. 3 s; Tables 1 , 2 ). The tyrosine-like component has been
detected at Ex/Em = 270-275/303-314 nm (peak T-region) and at 230/304 nm
(peak T UV -region) in a tyrosine standard dissolved in Milli-Q water, and at
275/304 and 230/307 nm when the standard was dissolved in seawater; at
265-280/293-313 nm in rivers and other freshwater systems; at 275/<300 nm in
lakes; at 275/304-306 nm in estuaries; at 270-275/299-332 nm in sea water; at
275/304-306 in soil; at 270/310 nm in water extracted from sugar maple leaves;
at 270/306 nm in drinking water treatment plants; and at 273/309 nm in plant
biomass, animal manure and soil (Fig. 3 s; Tables 1 , 2 ) (Coble 1996 ; Parlanti et
al. 2000 ; Yamashita and Tanoue 2003a ; Mostofa and Sakugawa 2009 ; Nakajima
2006 ; Provenzano et al. 2004 ; Lu and Allen 2002 ; Zhang et al. 2009a ; Hunt et al.
2008 ; Kowalczuk et al. 2009 ; Baghoth et al. 2010 ; Chen et al. 2010 ; Fellman et
al. 2008 , 2009 , 2010 ; Yamashita et al. 2010 , 2011 ; Murphy et al. 2008 ; Yamashita
and Jaffé 2008 ). Tryptophan and tyrosine when present together in peptides (com-
ponent 4) are detected from two peaks at Ex/Em = 275/306, 338 nm (T-region)
during algal blooming periods, as derived from a mesocom experiment (Table 2 )
(Stedmon and Markager 2005a ). Tyrosine is derived microbially from algal bio-
mass in freshwater and marine environments (Coble 1996 ; Yamashita and Tanoue
2003a ; Stedmon and Markager 2005a ; Determann et al. 1998 ). Comparison of
tyrosine and trytophan concentrations with their respective fluorescence intensities
+
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