Communication
RSC Advances
acid residues and forming minimum number of hydrogen bonds
with adjacent amino acids (Fig. 3S(b)†). This nding explains why
TRIS appears the strongest and TAPS appears the weakest buffer in
enhancing the activity of a-CT. TES buffer is less hydrophobic and
more polar than TAPS and TAPSO buffer. Thus, the observed
electrostatic interactions, including hydrogen bonding, in TES
system are stronger than those in TAPS or TAPSO system. Since
these interactions are stabilizing the native conformation of the
enzymes, this might be the reason, why TES buffer is more
promising in enhancing catalytic activity of a-CT in comparison
with TAPS or TAPSO. TAPS and TAPSO buffers are structurally
similar, except the presence of an extra hydroxyl group (–OH)
between the amino and the sulfonic group in TAPSO. It is inter-
esting to see that this extra hydroxyl group of TAPSO involved in
the hydrogen bonding with Gln34 and Gly38 (Fig. 3S(c)†). It might
be the reason for the enhanced catalytic activity of the a-CT in
TAPSO over TAPS. Thus, the outcomes from molecular docking are
in agreement with the experimental ndings. From this series of
2 V. V. Levitsky, P. Lozano and J. L. Iborra, Biotechnol. Lett.,
1999, 21, 595–599.
´
´
3 L. M. Simon, M. Kotorman, G. Garab and I. Laczko, Biochem.
Biophys. Res. Commun., 2001, 280, 1367–1371.
4 B. S. Gupta, M. Taha and M. J. Lee, Process Biochem., 2013, 48,
1686–1696.
5 A. A. Vinogradov, E. V. Kudryashova, V. Y. Grinberg,
N. V. Grinberg, T. V. Burova and A. V. Levashov, Protein
Eng., 2001, 14, 683–690.
6 A. Kumar and P. Venkatesu, Chem. Rev., 2012, 112, 4283–
4307.
7 A. Kumar, P. Attri and P. Venkatesu, Thermochim. Acta, 2012,
536, 55–62.
8 P. Attri, P. Venkatesu and M. J. Lee, J. Phys. Chem. B, 2010,
114, 1471–1478.
9 J. Wyman and S. Gill, Binding and linkage: functional
chemistry of biological molecules, University science books,
California, Mill Valley, 1990.
systematically studies, it is revealed that the investigated buffers 10 S. N. Timasheff and T. Arakawa, Stability of protein structure
are not only suitable for maintaining the required pH value in
aqueous solutions but also can be used to enhance the activity of
enzymes.
by solvents, in Creighton TE editors. Protein Structure: A
Practical Approach, Oxford University Press, Oxford, 1989.
11 S. N. Timasheff, Annu. Rev. Biophys. Biomol. Struct., 1993, 22,
67–97.
12 S. N. Timasheff, Adv. Protein Chem., 1998, 51, 356–432.
13 M. T. Record, W. Zhang and C. Anderson, Adv. Protein Chem.,
1998, 51, 282–355.
14 K. Rawat and H. B. Bohidar, J. Phys. Chem. B, 2012, 116,
11065–11074.
15 D. H. Dagade, K. R. Madkar, S. P. Shinde and S. S. Barge, J.
Phys. Chem. B, 2013, 117, 1031–1043.
16 M. Bekhouche, L. J. Blum and B. Doumeche, J. Phys. Chem. B,
2012, 116, 413–423.
17 Y. Akdogan, M. J. N. Junk and D. Hinderberger,
Biomacromolecules, 2011, 12, 1072–1079.
18 C. A. Summers and R. A. Flowers II, Prot. Sci., 2000, 9, 2001–
2008.
19 N. Spetri, F. Alfani, M. Cantarella, F. D. Amico, R. Germani
and G. Savelli, J. Mol. Catal. B: Enzym., 1999, 6, 99–110.
20 P. Viparelli, F. Alfani and M. Cantarella, J. Mol. Catal. B:
Enzym., 2001, 15, 1–8.
21 P. Viparelli, F. Alfani and M. Cantarella, J. Mol. Catal. B:
Enzym., 2003, 21, 174–187.
Conclusions
The catalytic activity of enzyme a-CT was analyzed in the pres-
ence of the commonly used biological buffers: TRIS, TES, TAPS,
and TAPSO. Interestingly, all the studied buffers were found to
enhance the activity of enzyme and the activity enhancement
increases with increasing buffer concentration. Since the enzy-
matic catalyzed processes are widely used and are highly
important from industrial point of view, the current study can
help in the improvement of such process in a more economical
way. In addition, we investigated the mechanism of the inter-
action of these buffers with a-CT. From the series of carefully
performed analysis on buffer-a-CT systems, the results reveal
that the buffer molecules, at higher concentrations, provide
more compact conformation to the enzyme. The main interac-
tion between buffer and a-CT is electrostatic. Certainly, such
information can help in the better understanding of the process
based on the buffer–enzyme systems. Therefore, employing
buffer as an enzyme stabilizer or an activity enhancer can be an
advantageous alternative over using the traditional volatile
organic compounds and the expensive modern ionic liquids.
22 P. Viparelli, F. Alfani and M. Cantarella, Biochem. J., 1999,
344, 765–773.
23 P. Attri, P. Venkatesu and A. Kumar, Phys. Chem. Chem. Phys.,
2011, 13, 2788–2796.
Acknowledgements
24 D. G. Dalgleish, in Emulsions and emulsion stability, ed. J.
Sjoblom, New York, Marcel Dekker, 1996, ch. 5.
25 P. Attri, P. Venkatesu and M. J. Lee, J. Phys. Chem. B, 2010,
114, 1471–1478.
26 B. F. Erlanger, N. Kokowsky and W. Cohen, Arch. Biochem.
Biophys., 1961, 95, 271–278.
The authors gratefully acknowledge the nancial support from
the National Science Council, Taiwan, through Grant no.
NSC102-2811-E-011-014 and NSC 102-2221-E011-137-MY3.
27 T. De-Diego, P. Lozano, S. Gmouth, M. Vaultier and
J. L. Iborra, Biotechnol. Bioeng., 2004, 75, 916–924.
Notes and references
1 E. V. Kudryashova, A. K. Gladilin, A. V. Vakurov, F. Heizt, 28 G. R. Castro, Enzyme Microb. Technol., 2000, 27, 143–150.
A. V. Levashov and V. V. Mozhaev, Biotechnol. Bioeng., 1997, 29 M. Taha and M. J. Lee, Phys. Chem. Chem. Phys., 2010, 12,
55, 267–277.
12840–12850.
This journal is © The Royal Society of Chemistry 2014
RSC Adv., 2014, 4, 51111–51116 | 51115