Abstract
| Language | English |
|---|---|
| Pages | 231 |
| Journal | Food Chemistry |
| Volume | 48 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - 1993 |
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A test for the two-stage thermoinactivation model for chymotrypsin. / Owusu, RK; Berthalon, N.
In: Food Chemistry, Vol. 48, No. 3, 1993, p. 231.Research output: Contribution to journal › Article
TY - JOUR
T1 - A test for the two-stage thermoinactivation model for chymotrypsin
AU - Owusu, RK
AU - Berthalon, N
PY - 1993
Y1 - 1993
N2 - Chymotrypsin was irreversibly inactivated at 30–130°C, pH 1.0–7.0 and in the presence of 0–4.0 m guanidine hydrochloride (GnHCl). The activation enthalpy for enzyme thermoinactivation (Δ#) at moderate temperatures, pH 4.0–7.0 and in ≤2 m GnHcl was 175–322 kJ mol−1. The activation entropy (ΔS#) was 244–734 J mol−1 K−1. Such results are compatible with enzyme unfolding being the rate-determining step for the thermoinactivation of native chymotrypsin. For chymotrypsin pre-unfolded at low pH, high temperature and/or in Gn/HCl, ΔH# was 30–40 kJ mol−1 and ΔS# was between −182 and −191 J mol−1 K−1. Therefore, thermoinactivation of pre-unfolded chymotrypsin is likely to involve covalent bond lysis as the rate-determining step. A biphasic Arrhenius plot was obtained for chymotrypsin thermoinactivation in 1.0–1.5 m GnHCl. Taken together, these results provide strong support for the two-stage model for enzyme thermoinactivation.
AB - Chymotrypsin was irreversibly inactivated at 30–130°C, pH 1.0–7.0 and in the presence of 0–4.0 m guanidine hydrochloride (GnHCl). The activation enthalpy for enzyme thermoinactivation (Δ#) at moderate temperatures, pH 4.0–7.0 and in ≤2 m GnHcl was 175–322 kJ mol−1. The activation entropy (ΔS#) was 244–734 J mol−1 K−1. Such results are compatible with enzyme unfolding being the rate-determining step for the thermoinactivation of native chymotrypsin. For chymotrypsin pre-unfolded at low pH, high temperature and/or in Gn/HCl, ΔH# was 30–40 kJ mol−1 and ΔS# was between −182 and −191 J mol−1 K−1. Therefore, thermoinactivation of pre-unfolded chymotrypsin is likely to involve covalent bond lysis as the rate-determining step. A biphasic Arrhenius plot was obtained for chymotrypsin thermoinactivation in 1.0–1.5 m GnHCl. Taken together, these results provide strong support for the two-stage model for enzyme thermoinactivation.
U2 - 10.1016/0308-8146(93)90132-Y
DO - 10.1016/0308-8146(93)90132-Y
M3 - Article
VL - 48
SP - 231
JO - Food Chemistry
T2 - Food Chemistry
JF - Food Chemistry
SN - 0308-8146
IS - 3
ER -