Figure 1.
Molecular structure of TC and CTC (with atom numbers).
Figure 2.
(A) Effect of TC (CTC) on trypsin fluorescence (corrected). (B) Stern-Volmer plots for the quenching of trypsin by TC and CTC at different temperatures (corrected).
Data represent the mean ± SD of three independent experiments. Conditions: (A) trypsin (5×10−6 mol L−1) with different concentrations of TC and CTC (×10−5 mol L−1, a, 0; b, 1; c, 2; d, 3; e, 4; f, 5); g: TC (CTC) only, concentration 5×10−5 mol L−1; pH 7.6; T = 298 K. (B) trypsin concentration: 5×10−6 mol L−1; pH 7.6.
Table 1.
Stern-Volmer quenching constants for the interaction of TC (CTC) with trypsin at different temperatures.
Table 2.
Binding constants and relative thermodynamic parameters of the TC (CTC)-trypsin system.
Table 3.
Energy transfer parameters between TC (CTC) and trypsin.
Figure 3.
Effect of TC and CTC on the activity of trypsin.
Data represent the mean ± SD of three independent experiments. Conditions: trypsin (1.67×10−6 mol L−1) with different concentrations of TC and CTC (×10−5 mol L−1, a, 0; b, 10; c, 20); pH 7.6; T = 298 K.
Figure 4.
Lineweaver-Burk plots of trypsin in the presence (blue circle) and absence (red circle) of TC (CTC), and the schematic diagrams for the binding of TC and CTC with trypsin.
Data represent the mean ± SD of five independent experiments. Conditions: trypsin concentration: 1.67×10−6 mol L−1; TC and CTC concentration: 3.33×10−5 mol L−1; pH 7.6.
Figure 5.
The binding mode between TC (CTC) and trypsin.
Trypsin is shown in cartoon. The interacting side chains of trypsin are displayed in surface mode. TC and CTC are represented using balls and stick. The atoms of TC and CTC are color-coded as follows: O, red; N: blue; C, green; H, white.
Figure 6.
The molecular modeling of interaction between TC (CTC) and trypsin.
The atoms of TC and CTC are marked with blue and the atoms of amino acid residues of trypsin are labeled with gray. The hydrogen bonds between TC (CTC) and trypsin are indicated by pink dashed line. The van der Waals interactions are illustrated with green dashed line.
Figure 7.
Conditions: trypsin (4×10−5 mol L−1) with different concentrations of TC and CTC (×10−5 mol L−1, a, 0; b, 2; c, 6; d, 10; e, 15; f, 20) (vs the same concentration of TC (CTC) solution); pH 7.6; T = 298 K.
Figure 8.
Synchronous fluorescence spectra of trypsin (corrected).
(A) Δλ = 15 nm and (B) Δλ = 60 nm. Conditions: trypsin (5×10−6 mol L−1) with different concentrations of TC and CTC (×10−5 mol L−1, a, 0; b, 1; c, 2; d, 3; e, 4; f, 5); pH 7.6; T = 298 K.
Figure 9.
CD spectra of trypsin and the trypsin-TC (CTC) system at room temperature.
Conditions: trypsin (5×10−5 mol L−1) with 0 or 5×10−5 mol L−1 TC (CTC); pH 7.6.
Table 4.
The effects of TC (CTC) on the percentage of secondary structural elements in trypsin.