Thermodynamic and activation parameters for the hydrolysis of amylose with Bacillus α-amylases in a diluted anionic surfactant solution

JOURNAL OF BIOSCIENCE AND BIOENCINEERING Vol. 93, No. $485-490. 2002

Thermodynamic and Activation Parameters for the Hydrolysis of Amylose with Bacillus a-Amylases in

a Diluted Anionic Surfactant Solution ATSUSHI TANAKA’ AND EIICHI HOSHIN02*

Wakayama Research Laboratories, Kao Corporation, 1334 Minato, Wakayama, Wakayama 640-8580, Japan’ and Tokyo Research Laboratories, Kao Corporation, 2-l-3 Bunka, Sumida-ku, Tokyo 131-8501, Japan2

Received 1 October 200 l/Accepted 13 February 2002

The effects of an anionic surfactant, sodium dodecyl sulfate (SDS), on the kinetic behavior in the hydrolysis of amylose with two bacterial a-amylases from Bacillus amyloliquefaciens and B. Iicheniformis were studied. The catalytic rates of both amylases in the present study showed sigmoidal kinetics with increased concentration of added SDS; the rates were increased in the range below the critical micelle concentration (cmc) and then markedly decreased above the cmc. The catalytic rate of the a-amylase from B. amyloliquefaciens was more sensitive to the added surfactant than that of the a-amylase from B. Iicheniformis. The diluted SDS at concentrations below the cmc was responsible for the preferential formation of the enzyme-substrate (E-S) complex, and the hydrolytic catalysis of both enzymes was apparently accelerated. Thermodynamic parameters for the E-S complex formation revealed that the apparent enthalpy and entropy changes of both amylases were increased by the addition of the diluted SDS. It is suggested that the increase in hydrolytic rate by the addition of SDS is due to the larger increase in the entropy changes for the E-S complex formation than in the enthalpy changes.

[Key words: a-amylase, hydrolysis, surfactant, kinetics, thermodynamics, activation parameter, Bacillus amyloliquefaciens, Bacillus licheniformis]

a-Amylase (EC 3.2.1.1, 1,4-CL-D-glucan glucanohydro- lase) hydrolyses starch by cleaving the internal CX- 1,4-gluco-

sidic bonds in an endo-fashion (14). Kinetic studies of the amylases produced by members of the genus Bacillus have been carried out (5,6), but a detailed study in aqueous solutions of surfactant has not been performed because the solution systems are too complex. Enzyme reactions in surfactant solution must be elucidated for the benefit of the food and detergent industries (7, 8). Furthermore, surfactants in aqueous solutions form a wide variety of aggregated micelles and vesicles, and they provide a model for studies of biological membranes.

An increasing use of a-amylases in biotechnology has been occurred due to the wide variety of conditions such as high temperature, extreme pH, and the presence of surfactants and organic solvents (7, 8). An anionic surfactant, sodium dodecyl sulfate (SDS), is used in estimating poly- peptide sizes, either by gel electrophoresis or by molecular- sieve chromatography (9). Knowledge regarding SDS-protein interactions can be useful for understanding and further developing this important method. Furthermore, surfactants are a widely used tool in the characterization and study of soluble and membrane proteins (10). Recently, some re- searchers demonstrated structural similarity among protein

* Corresponding author. e-mail: [email protected] phone: +81-(0)3-5630-7462 fax: +81-(0)3-5630-7440

complexes with large unilamellar phospholipid vesicles and SDS (11-15). Thus, these studies can provide not only information on numerous biotechnological applications but also simple models for studies of the correlations between structure, function, and stability in the presence of biological membranes.

In the present study, we investigated the hydrolysis of soluble amylose (average degree of polymerization, DP, is 18) by a-amylases from Bacillus amyloliquefaciens and B. licheniformis in an aqueous solution of SDS. For measurements, surfactant concentrations were chosen to be below the critical micelle concentration (cmc), where the enzymatic hydrolysis was accelerated. We investigated the effects of temperature on the rate of hydrolysis and determined the thermodynamic and activation parameters in the presence of the anionic surfactant. The hydrolytic process might be influenced not only by a change in polarity around the active site of enzymes but also by that around the substrate, because the interaction of amylose in aqueous solution with surfactants is highly probable. The level of interaction of SDS with amylose was determined by surface tension measurement.

MATERIALS AND METHODS

Enzyme and substrate A purified preparation of a-amylase from B. amyloliquefaciens was purchased from Seikagaku Kogyo (Tokyo). The enzyme was dissolved in 10 mM Tris-HCI buffer (pH

485

486 TANAKA AND HOSHINO

9.0) and loaded onto a gel-filtration column (2.6 cm i.d. x 80 cm) of Toyopearl HW-55 (Tosoh, Tokyo) that had been equilibrated with the same buffer. The a-amylase fraction was eluted at a flow rate of 1.5 ml/min and the eluted enzyme was dialyzed against distilled water at 5°C for 24 h. A purified preparation of a-amylase from B. Zichenzjbrrnis was purchased from Sigma Chemical (St. Louis, MO, USA). The enzyme was precipitated with 75% (w/v) am- monium sulfate and then further purified as reported previously (16). After dialysis against distilled water, the a-amylase from B. licheniformis preparation was loaded onto a gel-filtration column of Toyopearl HW-55 as described above (pH 9.0). The eluted fraction of a-amylase was loaded onto an ion-exchange column (5.2 cm i.d. x 50 cm) of DEAE-Toyopearl 650s (Tosoh) that had been equilibrated with 10 mM Tris-HCl buffer (pH 9.0), and then it was eluted with a linear gradient of NaCl (0 to 0.1 M). The eluted enzyme was dialyzed against distilled water at 5°C for 24 h. The molecular weights of highly purified a-amylases from B. umylo- liquefaciens and B. Iicheniformis were estimated to be approx- imately 49,000 and 63,000 by SDS-polyacrylamide gel electrophoresis, respectively. The concentrations of the enzymes were confirmed spectrophotometrically employing a molar extinction coefficient at 280 nm of 106,000 M-‘cm-’ for a-amylase from B. amyloliquefaciens and 105,000 M-‘cm-’ for a-amylase from B. Zicheniformis. Water-soluble amylose (DP, 18) was purchased from Hayashibara Biochem. Lab. (Okayama). The reducing end of the substrate was decomposed by treatment with sodium borohydride for the measurement of the saccharifying activity of enzymes as reported previously (17).

Determination of the surface tension of SDS solutions SDS was purchased from Wako Pure Chemical Industries (Osaka). The surface tension of the SDS aqueous solution was measured by Wilhelmy’s method (18), using a platinum plate with a 2.0 cm pe- rimeter and an automatic tensiometer (CBVP-A3; FACE, Tokyo). The surfactant solution consisted of 25 mM Tris-acetate buffer (PH 7.0) with or without the soluble amylose. Determinations were taken at least every 10 min and the constancy of the surface tension versus time was verified in every solution. Every measurement was carried out at 25°C.

Measurement of the rate of enzymatic hydrolysis The reaction mixture consisted of 0.05 to 0.5% (w/v) soluble amylose (DP, 18), 25 mM Tris-acetate buffer (pH 7.0) with and without SDS below its cmc (3.50x 10m5M), and 6.50~10~‘” to2.60~ 10m9M a-amylase from B. amyloliquefaciens or 2.50 x 1 0m9 to 5.00 x 1 0m9 M a-amylase from B. licheniformis. After incubation for appropri- ate periods of time, the reducing power produced in the superna- tant was measured by the dinitrosalycylic acid method (19). The maximum rate of enzymatic hydrolysis (V,ax) and the dissociation constant of the enzyme-substrate (E-S) complex (K,,,) were estimated by a Lineweaver-Burk plot. The changes in enthalpy (AP) and entropy (AP) for the E-S complex formation were calculated with K,,, values at given temperatures (20 to 35°C) according to the following equation:

K,,-‘=exp(-WlRT+hSOIR) (1)

where R and Tare the gas constant and absolute temperature, respectively. The activation enthalpy (m) and entropy (A$) for the enzymatic hydrolysis were calculated with V_ values at given temperatures (20 to 35°C) according to the following equation:

Vnlax=k.&l (2) k,,= kTlh exp(-@lRT+ SIR) (3)

where k,,, k, h, and [E,] are rate constant for the enzymatic hydrolysis, Boltzmann’s constant, Planck’s constant, and the initial enzyme concentration, respectively. The reproducibility of the data was confirmed by the values for duplicate runs.

J. BIOSCI. BIOENG.,

RESULTS

Figure 1 shows the relative hydrolytic rates of amylose by a-amylases from B. amyloliquefaciens and B. licheniformis as a function of the concentration of SDS. The catalytic rates of the two types of a-amylases were increased by the addition of SDS at concentrations below the cmc, and adversely, they were markedly decreased with an increase in the concentration above the cmc. The catalytic rate of a- amylase from B. amyloliquefaciens was more sensitive to the added surfactant than that of a-amylase from B. Zicheni- formis. The increase in the rate amounted to 10% for a- amylase from B. amyloliquefaciens and less than 5% for a- amylase from B. lichenzjbrmis, and the decrease amounted to more than 70% for a-amylase from B. amyloliquefaciens and 20% for a-amylase from B. licheniformis.

Lineweaver-Burk plots for the enzymatic hydrolysis in the presence and absence of the diluted SDS were shown to be linear relationships and the apparent kinetic parameters obtained, Km and kc,,, are listed in Table 1. The k,, value for a-amylase from B. amyloliquefaciens was reduced and the K,,-’ value, which indicates the degree of E-S complex formation, was increased by the addition of SDS at concentrations below the cmc (3.50x 10” M) at 25°C. Therefore, the increase in the apparent catalytic rate of the a-amylase was due to the preferential E-S complex formation rather than to the catalytic efficiency (k,,). On the other hand, both the K,,-’ and k,,, values for a-amylase from B. licheniformis were increased by SDS. However, the increase in the k,,, for the a-amylase was within experimental error, thus the apparent increase in the catalytic rate of a-amylase from B. licheniformis was also contributed to by the preferential E-S complex formation. The dependence of the rate of hydrolysis on temperature, the plots of In K,,-’ and In k,, versus re- ciprocal absolute temperature (l/T), is shown in Figs. 2 and 3. The thermodynamic and activation parameters were de-

140 I

0.1

[SDS] (1 O-3 M)

FIG. 1. Effect of added SDS on the hydrolytic rates of a-amylases from B. amyloliquefuciens (closed circle) and B. licheniformis (open circle) against s&&e arnyfose. Each a-‘&ylase was incubated‘ with amvlose (DP. 181 at 25°C in 25 mM Tris-acetate buffer CDH 7.0) con- tailing various doncentrations of SDS. The hydrolytic ;8te fo; each concentration of SDS was converted to a relative value based on the hydrolytic rate in the absence of SDS.

VOL. 93,2002 EFFECTS OF SURFACTANT ON a-AMYLASE CATALYSIS 487

TABLE 1. Thermodynamic and activation parameters for the E-S complex formation and the hydrolysis of soluble amylose in SDS aqueous solutions at 2W.Z and pH 7.0

[SW (lo-‘M) (1041/mol.s) (kkdl)

LK, AGO W m AG’ AHt ti (kJ/mol) (kJ/mol) (J/mol.K) (l$$) (kJ/mol) (kJ/mol) (J/m01 .K)

BAA” 0 4.83f0.52 12.6f0.4 -6.14f0.08 23.2fl.l 98.4fO.l 38.3k2.9 52.5 kO.2 26.6kl.6 -87.OkO.2 3.50 6.12f0.46 18.6f0.2 -7.08f0.03 45.1 f7.0 175fl 32.9f2.1 52.9fO.l 37.5k2.7 -51.7kO.3

BLAb 0 4.13f0.18 152+_2 -12.5rtO.l -10.4kO.6 6.9450.07 2.72kO.08 59.1 f0.1 34.7k4.6 -81.8f0.6 3.50 4.52kO.17 16Ok3 -12.6kO.l -8.22k0.86 14.7fO.l 2.83+0.05 59.OkO.l 31.8zk4.7 -91.2f0.6

a a-Amylase from B. atnyloliquefaciens. b a-Amy&e from B. lichenzfirmis.

9.5

9.0

3 8.5

s 8.0

7.5

7.0 i

(a)

3.1 3.2 3.3 3.4 3.5

1/T(10-3K-‘)

4.0 I

3.5 - 03)

‘; 3.0 - d

c 2.5 -

2.0 -

3.1 3.2 3.3 3.4 3.5

1/T(10-3K-')

FIG. 2. Arrhenius (a) and van? Hoff(b) plots for the hydrolysis of soluble amylose with a-amylase from B. amyloliquefaciens. The a- amylase was incubated with amylose (DP, 18) in 25 mM Tris-acetate buffer (pH 7.0) in the absence (open circle) and presence of SDS below the cmc (3.50x 10m5 M) (closed circle).

termined according to the linear relationships of the plots and the obtained values are summarized in Table 1. The entropy changes for the E-S complex formation of both enzymes were increased by the addition of SDS below the cmc. It is suggested that the increase in the hydrolytic rate in the presence of SDS was mainly due to the difference in the entropy changes for E-S complex formation with and without SDS. The activation entropies for the catalytic efficiency of both amylases showed apparently negative values both in the absence and in the presence of SDS below its cmc.

The variations in the surface tension as a function of SDS concentration in the various concentrations of amylose solu-

6.5

(a) 6.0 -

$5.5. \

5.0 -

4.5 a 1 I

5.5

5.0

>

_C 4.5

4.0

3.1 3.2 3.3 3.4 3.5

llT(10-3K-1)

(b)

3.1 3.2 3.3 3.4 3.5

lIT(lO"K-')

FIG. 3. Arrhenius (a) and van’t Hoff(b) plots for the hydrolysis of soluble amylose with a-amylase from B. lichenzjimnis. The a-arny- lase was incubated with amylose (DP, 18) in 25 mM Tris-acetate buffer (pH 7.0) in the absence (open circle) and presence of SDS below the cmc (3.50x lo-‘M) (closed circle).

tions are shown in Fig. 4. The value of the cmc (5.00x 10m3 M) was not apparently changed by the addition of amylose, while the surface tension value below the cmc increased. According to the classical theory (20), it is evident from Fig. 4 that the surfactant is bound to the amylose in the amylose-SDS system.

DISCUSSION

Many surfactants, which interact with protein, are known to have distinct electrostatic and hydrophobic regions in aqueous solution and alter the secondary or tertiary structures of the protein (21). In particular, many enzymes are

488 TANAKA AND HOSHINO J. B~OSCI. BIOENG.,

20 I ' ' '1ll.J ' "~~~~.' t ".,,IJ

0.1 1 10 100

[SDS] (1 O-3M)

FIG. 4. Variation of the surface tension of amylose solution at 25’C versus the logarithm of the SDS concentration. Amylose concentrations were 0 (open circle), 0.125 (closed triangle), and 0.5% (w/v) (closed circle) in 25 mM Tris-acetate buffer (pH 7.0).

unstable and unfold in solutions of anionic surfactants such as SDS (22). It is also known that the amylose used as a substrate interacts with SDS, where the surfactant molecules are included in the amylose helix (23, 24). Therefore, the hydrolytic catalysis would be influenced not only by the distinction of the polarity but also by changes in the enzyme and the substrate structures. Furthermore, the micelle formation of surfactants may effect the kinetic behavior of enzymes. The catalytic rates of a-amylases from B. amyloliquefaciens and B. licheniformis in the present study showed sigmoidal kinetics with increased concentration of added SDS; the rates were increased in the range below the cmc and then markedly decreased above the cmc. Thus, the non-aggregated SDS molecules are considered to accelerate the hydrolysis due to their interaction with amylose and ct- amylases, whereas the aggregated SDS micelles have the ability to inhibit the reaction.

The activation entropies of the two types of a-amylases showed apparently negative values both in the absence and presence of SDS below its cmc. The attack of an activated water molecule for the hydrolysis on the E-S complex in- volves the movement of one water molecule from the liquid state to the enzyme active site, which uses about 10 J/mole K of the entropy cost (25). It is suggested that the cooperative behavior of other water molecules around the active site induced the large negative values of activation entropy for the present hydrolytic catalysis. When one water molecule binds to the active site in the amylases, the glutamic acid (Glu) and the aspartic acid (Asp) residues in the active site act as a catalytic acid and a catalytic base, respectively (26). Hydrolytic catalysis of lysozyme, glucoamylase, and a- and P-amylases proceed via a three-step mechanism in which the first step is the formation of an E-S complex, the second step is the formation of the carbonium ion intermediate, and the third step is the release of the hydrolytic product from the intermediate (26). Under acidic conditions, the carboxy- late group of the Glu residue is promoted to accept a proton, and then the release of the product would become a rate limiting step (27). Because the optimum pH for the activity

of a-amylases from B. amyloliquefaciens and B. licheniformis is in the acidic region, it is assumed that the rate limiting step would be the formation of the carbonium ion intermediate at neutral pH (7.0) as in the present study. A subsequent hydration or dehydration step at the enzyme active site is proposed (Fig. 5). During the formation of the carbonium ion intermediate, some water molecules can be moved to the active site positions in the transition state and the apparent activation entropy would become a more negative value. The large negative values of the activation entropy are attributed to the cooperative adjustment of the water molecules to the charged transition state during the formation of the carbonium ion intermediates (rate limiting step) (Fig. 5).

Amylose with a- 1,4-D-glucosidic linkages forms coil structures in aqueous solution and helical inclusion complexes with various mono-chained ligands (23). The coil structures are flexible and include six to eight glucose units per turn depending on the type of ligand, and both the head- group properties and the length of the hydrocarbon tails of SDS as a ligand have an influence on the properties of the complex with the coils (28). In this study, the corresponding binding of SDS with amylose was confirmed by the surface tension measurement (20). For the kinetic analysis, we ex- amined the hydrolytic catalysis at various concentrations of amylose so that the observed kinetic parameters became apparent data. The effects of the surfactant on the reaction kinetics might be due to the effects of amylose-bound SDS rather than to the effects of direct interaction with the free SDS.

The increases in the k,,JK, values for a-amylases from B. amyloliquefaciens and B. licheniformis as a result of the addition of SDS below its cmc are mainly attributed to the decrease in K,,, values; i.e., the preferential formation of the E-S complex. The entropy changes for the E-S complex formation in the presence of SDS for the a-amylases were larger than the changes in the SDS-free systems. Thus, the entropic factors made a larger contribution than the en- thalpic factors to the E-S complex formation. The difference in the entropy change [A(AP)] in the presence and absence of SDS for the E-S complex formation of a-amylase from B. amyloliquefaciens was 77 J/mol.K at 25°C in the present study. This value was higher than the difference for the complex formation of a-amylase from B. Zichenzjbrmis [A(A,Y)=7.8 J/mol.K]. This could be postulated to involve hydration around the active site of the enzymes. Entropy is gained when bound water is expelled into bulk water, which is generally accepted as a driving force for E-S complex formation (29, 30). The increase in As” may be due to the increased amount of dehydration required for the complex formation. In a recent study, it was reported that SDS- induced enzyme activation was related to loosening of the tightly packed tetrameric protein structure upon the addition of the surfactant (15, 31). It is known that a-amylase from B. Zichenzjb-mis is structurally stable in comparison with a- amylase from B. amyloliquefaciens (32). Suzuki et al. (32) suggested that the difference in the stability of both amylases was due to differences in the degree of internal packing. Loosening of the internal packing might be responsible for the increase in the amount of water molecules around

VOL. 93.2002 EFFECTS OF SURFACTANT ON a-AMYLASE CATALYSIS 489

ENZYME

, . ;“;;;;;;;, ::,“.’ :I;;, ‘-\ Cooperative water adjustment 1 Aspf o’H ‘+Iu

ENZYME

FIG. 5. Proposed mechanism of a-amylase catalyzed hydrolysis of amylose. The rate limiting step in the present study is the formation of the carbonium ion intermediate. The amount of water molecules moving to the active site to reach the transition state is increased and negative values were obtained for the activation entropy.

enzymes and thus the increase in the entropy changes of both a-amylases.

Anionic surfactants which undergo micelle formation are known to alter protein and carbohydrate conformations. It is known that SDS-induced enzyme activation is related to loosening of tightly packed structures (15,3 l), and this phe- nomenon is very similar to that observed in previous studies of some proteins in the presence of anionic phospholipid vesicles (33). It may be suggested that the enhancement of the catalytic rates of a-amylases from B. amyloliquefaciens and B. licheniformis in the diluted SDS solution is caused by mechanisms similar to those involved in the enhancement of enzyme activity via binding to the anionic phospholipid interface. Because phospholipid vesicles are very unstable and insoluble in aqueous solutions, studies in the presence of surfactant molecules below their cmc can be a strategy for studying the mechanism of enzymatic reactions in the presence of biological membranes.

REFERENCES

Robyt, J. F. and Whelan, W. J.: The a-amylases, p. 430- 476. In Radley, J. A. (ed.), Starch and its derivatives, 4th ed. Chapman & Hall, London (1968). Takagi, T., Toda, H., and Isemura, T.: Bacterial and mold amylases, p. 235-271. In Bayer, P. D. (ed.), The enzymes, 3rd ed. Academic Press, New York (1971). Fogarty, W. M. and Kelly, C. T.: Amylases, amyloglucosi- dases and related glucanases, p. 115-l 70. In Rose, A. H. (ed.), Microbial enzymes and bioconversions. Academic Press, London (1980). Kindle, K. L.: Characteristics and production of thermostable

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

a-amylase. Appl. Biochem. Biotech., 8, 153-170 (1983). Hiromi, K.: Interpretation of dependency of rate parameters on the degree of polymerization of substrate in enzyme-catalyzed reactions. Evaluation of subsite affinities of exoen- zyme. Biochem. Biophys. Res. Commun., 40, 16 (1970). Thoma, J. A., Brothers, C., and Spradlin, J.: Subsite map- ping of enzymes. Studies on Bacillus subtilis amylase. Bio- chemistry, 9, 1768-I 775 (1970). Kulp, K.: Carbohydrases, p. 53-122. In Reed, G. (ed.), En- zymes in food processing, 2nd ed. Academic Press, New York (1975). Tanaka, A. and Hoshino, E.: Study on the substrate specificity of a-amylases that contribute to soil removal in detergents. J. Surf. Deterg., 2, 193-199 (1999). Fish, W. W., Reynolds, J. A., and Tanford, C.: Gel chromatography of proteins in denaturing solvents. Comparison between sodium dodecyl sulfate and guanidine hydrochloride as denaturants. J. Biol. Chem., 245, 5 145-5 168 (1970). Garavito, R. M. and F.-Miller, S.: Detergents as tools in membrane biochemistry. J. Biol. Chem., 276, 32403-32406 (2001). Decker, H., Ryan, M., Jaenicke, E., and Temilliger, N.: SDS-induced phenoloxidase activity of hemocyanins from Limulus polyphemus, Eurypelma californicum, and Cancer magister. J. Biol. Chem., 276, 17796-17799 (2001). Rozek, A., Friedrich, C. L., and Hancock, R. E. W.: Struc- ture of the bovine antimicrobial peptide indolicidin bound to dodecylphosphocholine and sodium dodecyl sulfate micelles. Biochemistry, 39, 15765-15774 (2000). Chen, G. Q. and Gouaux, E.: Probing the folding and un- folding of wild-type and mutant forms of bacteriorhodopsin in micellar solutions. Biochemistry, 38, 15380-I 5387 (1999). Montserret, R., McLeish, M. J., Biickmann, A., Geourjon, C., and Penin, F.: Involvement of electrostatic interactions in the mechanism of peptide folding induced by sodium dodecyl sulfate binding. Biochemistry, 39, 8362-8373 (2000).

490 TANAKA AND HOSHINO J. BIOSCI. BIOENG.,

15. Muga, A., Arrondo, J. L. R., Bellon, T., Sancho, J., and Bernabeu, C.: Structural and functional studies on the interaction of sodium dodecyl sulfate with P-galactosidase. Arch. Biochem. Biophys., 300,451457 (1993).

16. Suzuki, A., Yamane, T., Ito, Y., Nisbio, T., Fujiwara, II., and Ashida, T.: Crystallization and preliminary crystallo- graphic study of bacterial a-amylases. J. Biochem., 108,379- 381 (1990).

17. Strumeyer, D. H.: A modified starch for use in amylose assays. Anal. Biochem., 19,61-71 (1967).

18. Padday, J. F.: The measurement of surface tension, p. lOl- 149. In Matijevic, E. (ed.), Surface and colloid science, vol. 1. Wiley-Interscience, New York (1969).

19. Bernfeld, P.: Amylases, a and j3. Methods Enzymol., 1, 149- 158 (1955).

20. Svensson, E., Gudmundsson, M., and Eliasson, A.-C.: Binding of sodium dodecylsulphate to starch polysaccharides quantified by surface tension measurements. Colloids Surf. B, 6,227-233 (1996).

21. Fendler, J. H. and Fendler, E. J.: Catalysis in micellar and macromolecular systems, p. 3 1 l-3 12. Academic Press, New York (1975).

22. Isemura, T. and Takagi, T.: Interaction of Taka-amylase A with surface active agent. J. Biochem., 46, 1637-1644 (1959).

23. Hui, Y., Russell, J. C., and Whitten, D. G.: Host-guest interactions in amylose inclusion complexes. J. Am. Chem. Sot., 105, 1374-1376 (1983).

24. Yamamoto, M., Harada, S., Nakatsuka, T., and Sano, T.: Hydrodynamic characterization of amylose-SDS complex by viscosity measurement. Bull. Chem. Sot. Jpn., 61,1471-1474 (1988).

25. Dunitz, J. D.: The entropic cost of bound water in crystals

and biomolecules. Science, 264,670 (1994). 26. Dixon, M. and Webb, E.C.: Enzymes, p. 138-164. Long-

man, London (1979). 27. Hartlev. B. S. and Kilbv. B.A.: The inhibition of chvmo-

trypsin”by diethyl p-nitrophenyl phosphate. Biochem. i, 50, 6722678 (1952).

28. Wulff, G: and ‘Kubik, S.: Circular dichroism and ultraviolet spectroscopy of complexes of amylose. Carbohydr. Res., 237, l-10 (1992).

29. Fersht, A. R., Shi, J.-P., K&-Jones, J., Lowe, D. M., Wilkinson, A. J., Blow, D. M., Brick, P., Carter, P., Waye, M. M. Y., and Winter, G.: Hydrogen bonding and biological specificity analyzed by protein engineering. Nature, 314,235- 238 (1985).

30. Street, I. P., Armstrong, C. R, and Withers, S. G.: Hydro- gen bonding and specificity. Fluorodeoxy sugars as probes of hydrogen bonding in the glycogen phosphorylase-glucose complex. Biochemistry, 25,60216027 (1986).

31. D’Auria, S., Cesare, N. D., Gryczynski, I., Rossi, M., and Lakowicz, J. R: On the effect of sodium dodecyl sulfate on the structure of P-galactosidase from Escherichia coli. A fluorescence study. J. Biochem., 130, 13-18 (2001).

32. Suzuki, Y., Ito, N., Yuuki, T., Yamagata, H., and Udaka, S.: Amino acid residues stabilizing a Bacillus a-amylase against irreversible thermoinactivation. J. Biol. Chem., 264, 18933-18938 (1989).

33. Kisselev, P., Wessel, R, Pisch, S., Bornscheuer, U., Schmid, R-D., and Schwarz, D.: Branched phosphatidylcholines stimulate activity of cytochrome P45OSCC (CYPllAl) in phospholipid vesicles by enhancing cholesterol binding, membrane incorporation, and protein exchange. J. Biol. Chem., 273, 1380-1386 (1998).

Documents

Thermodynamic and activation parameters for the hydrolysis of amylose with Bacillus α-amylases in a diluted anionic surfactant solution