Binding of Competitive Inhibitors to S-Chymotrypsin in the Alkaline pH Region. Competitive Inhibition Kinetics and Proton-Uptake Measurements

Pablo Valenzuela, Myron L. Bender

Resultado de la investigación: Article

33 Citas (Scopus)

Resumen

The binding of the three competitive inhibitors benzyl alcohol, tryptophol, and N-acetyl-D-tryptophanamide to α- and δ-chymotrypsins was studied over the pH range 7 to 11 by competitive inhibition kinetics using N-furyl-acryloyl-L-tryptophan methyl ester as substrate. The results indicate that the binding of these inhibitors to δ-chymotrypsin exhibits a pH dependence significantly different from the pH dependence obtained with α-chymotrypsin. Analysis of K, vs. pH profiles for the interaction of benzyl alcohol, tryptophol, and N-acetyl-D-tryptophanamide with δ-chymotrypsin indicates that the pKa of an ionizing group of the enzyme (9.2, 9.5, and 9.2, respectively) is shifted to a pKa of 10.0, 10.1, and 9.8, respectively, in the enzyme-inhibitor complex. This behavior differs from that of α-chymotrypsin, where, in agreement with previous reports, the binding of the three inhibitors was found to be strictly dependent on the ionization of a group in the enzyme with a pKa of 9.0 that apparently shifts upon binding of inhibitor to a value of 11.5 or higher. The proton uptake that accompanies the binding of the three inhibitors to δ-chymotrypsin was also measured as a function of pH. A good agreement between the measured proton uptake and the predicted values from the corresponding pKa shifts was found. It is concluded that the different behavior of α- and δ-chymotrypsins at high pH reflects a difference in the binding abilities of the enzymes. The present hypotheses regarding the conformation and activity of α-chymotrypsin at alkaline pH are discussed in the light of this particular behavior of δ-chymotrypsin.

Idioma originalEnglish
Páginas (desde-hasta)2440-2446
Número de páginas7
PublicaciónBiochemistry
Volumen9
N.º12
DOI
EstadoPublished - 1 jun 1970

Huella dactilar

Competitive Binding
Chymotrypsin
Protons
Kinetics
Benzyl Alcohol
Enzymes
Enzyme Inhibitors
Tryptophan
Ionization
Conformations

ASJC Scopus subject areas

  • Biochemistry

Citar esto

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title = "Binding of Competitive Inhibitors to S-Chymotrypsin in the Alkaline pH Region. Competitive Inhibition Kinetics and Proton-Uptake Measurements",
abstract = "The binding of the three competitive inhibitors benzyl alcohol, tryptophol, and N-acetyl-D-tryptophanamide to α- and δ-chymotrypsins was studied over the pH range 7 to 11 by competitive inhibition kinetics using N-furyl-acryloyl-L-tryptophan methyl ester as substrate. The results indicate that the binding of these inhibitors to δ-chymotrypsin exhibits a pH dependence significantly different from the pH dependence obtained with α-chymotrypsin. Analysis of K, vs. pH profiles for the interaction of benzyl alcohol, tryptophol, and N-acetyl-D-tryptophanamide with δ-chymotrypsin indicates that the pKa of an ionizing group of the enzyme (9.2, 9.5, and 9.2, respectively) is shifted to a pKa of 10.0, 10.1, and 9.8, respectively, in the enzyme-inhibitor complex. This behavior differs from that of α-chymotrypsin, where, in agreement with previous reports, the binding of the three inhibitors was found to be strictly dependent on the ionization of a group in the enzyme with a pKa of 9.0 that apparently shifts upon binding of inhibitor to a value of 11.5 or higher. The proton uptake that accompanies the binding of the three inhibitors to δ-chymotrypsin was also measured as a function of pH. A good agreement between the measured proton uptake and the predicted values from the corresponding pKa shifts was found. It is concluded that the different behavior of α- and δ-chymotrypsins at high pH reflects a difference in the binding abilities of the enzymes. The present hypotheses regarding the conformation and activity of α-chymotrypsin at alkaline pH are discussed in the light of this particular behavior of δ-chymotrypsin.",
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Binding of Competitive Inhibitors to S-Chymotrypsin in the Alkaline pH Region. Competitive Inhibition Kinetics and Proton-Uptake Measurements. / Valenzuela, Pablo; Bender, Myron L.

En: Biochemistry, Vol. 9, N.º 12, 01.06.1970, p. 2440-2446.

Resultado de la investigación: Article

TY - JOUR

T1 - Binding of Competitive Inhibitors to S-Chymotrypsin in the Alkaline pH Region. Competitive Inhibition Kinetics and Proton-Uptake Measurements

AU - Valenzuela, Pablo

AU - Bender, Myron L.

PY - 1970/6/1

Y1 - 1970/6/1

N2 - The binding of the three competitive inhibitors benzyl alcohol, tryptophol, and N-acetyl-D-tryptophanamide to α- and δ-chymotrypsins was studied over the pH range 7 to 11 by competitive inhibition kinetics using N-furyl-acryloyl-L-tryptophan methyl ester as substrate. The results indicate that the binding of these inhibitors to δ-chymotrypsin exhibits a pH dependence significantly different from the pH dependence obtained with α-chymotrypsin. Analysis of K, vs. pH profiles for the interaction of benzyl alcohol, tryptophol, and N-acetyl-D-tryptophanamide with δ-chymotrypsin indicates that the pKa of an ionizing group of the enzyme (9.2, 9.5, and 9.2, respectively) is shifted to a pKa of 10.0, 10.1, and 9.8, respectively, in the enzyme-inhibitor complex. This behavior differs from that of α-chymotrypsin, where, in agreement with previous reports, the binding of the three inhibitors was found to be strictly dependent on the ionization of a group in the enzyme with a pKa of 9.0 that apparently shifts upon binding of inhibitor to a value of 11.5 or higher. The proton uptake that accompanies the binding of the three inhibitors to δ-chymotrypsin was also measured as a function of pH. A good agreement between the measured proton uptake and the predicted values from the corresponding pKa shifts was found. It is concluded that the different behavior of α- and δ-chymotrypsins at high pH reflects a difference in the binding abilities of the enzymes. The present hypotheses regarding the conformation and activity of α-chymotrypsin at alkaline pH are discussed in the light of this particular behavior of δ-chymotrypsin.

AB - The binding of the three competitive inhibitors benzyl alcohol, tryptophol, and N-acetyl-D-tryptophanamide to α- and δ-chymotrypsins was studied over the pH range 7 to 11 by competitive inhibition kinetics using N-furyl-acryloyl-L-tryptophan methyl ester as substrate. The results indicate that the binding of these inhibitors to δ-chymotrypsin exhibits a pH dependence significantly different from the pH dependence obtained with α-chymotrypsin. Analysis of K, vs. pH profiles for the interaction of benzyl alcohol, tryptophol, and N-acetyl-D-tryptophanamide with δ-chymotrypsin indicates that the pKa of an ionizing group of the enzyme (9.2, 9.5, and 9.2, respectively) is shifted to a pKa of 10.0, 10.1, and 9.8, respectively, in the enzyme-inhibitor complex. This behavior differs from that of α-chymotrypsin, where, in agreement with previous reports, the binding of the three inhibitors was found to be strictly dependent on the ionization of a group in the enzyme with a pKa of 9.0 that apparently shifts upon binding of inhibitor to a value of 11.5 or higher. The proton uptake that accompanies the binding of the three inhibitors to δ-chymotrypsin was also measured as a function of pH. A good agreement between the measured proton uptake and the predicted values from the corresponding pKa shifts was found. It is concluded that the different behavior of α- and δ-chymotrypsins at high pH reflects a difference in the binding abilities of the enzymes. The present hypotheses regarding the conformation and activity of α-chymotrypsin at alkaline pH are discussed in the light of this particular behavior of δ-chymotrypsin.

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U2 - 10.1021/bi00814a008

DO - 10.1021/bi00814a008

M3 - Article

VL - 9

SP - 2440

EP - 2446

JO - Biochemistry

JF - Biochemistry

SN - 0006-2960

IS - 12

ER -