486
K. M. G. Mostofa et al.
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. 3q). 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. 3r), may confirm the peak
position of the T-region at longer wavelengths than the T UV -region. The fluorescence 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 fluorescence at the peak T-region than at the peak T UV -region (Fig. 3m, 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. 3r). Tryptophan is decomposed both photolytically 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 tryptophan 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. 3s; 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. 3s; 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 (component 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 biomass 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
K. M. G. Mostofa et al.
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. 3q). 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. 3r), may confirm the peak
position of the T-region at longer wavelengths than the T UV -region. The fluorescence 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 fluorescence at the peak T-region than at the peak T UV -region (Fig. 3m, 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. 3r). Tryptophan is decomposed both photolytically 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 tryptophan 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. 3s; 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. 3s; 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 (component 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 biomass 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