Aa. Panova et al., THERMAL-STABILITY OF IMMOBILIZED ALPHA-CHYMOTRYPSIN IS ADDITIONALLY INCREASED BY CHAOTROPIC COMPOUNDS, Biotechnology techniques, 9(1), 1995, pp. 13-18
Temperature dependence of the rate constant of irreversible thermal in
activation, k(in), of immobilized alpha-chymotrypsin depends markedly
on the number of covalent bonds between the enzyme and support. When t
he number of bonds is big enough (thirteen), the dependence is linear
as presented in Arrhenius plot (log k(in) versus reciprocal temperatur
e). However, if the number of such bonds is moderate or;small (six or
two), the temperature dependence of k(in) has a pronounced 'zig-zag' c
haracter. This difference in the inactivation behaviour is attributed
to an ability of 'moderately or mildly' attached alpha-chymotrypsins t
o accomplish a transition into a less ordered, catalytically inactive
conformation and to inability of 'rigidly' bound enzyme to pass such a
transition. Chaotropic salts additionally stabilize this loose confor
mation of 'mildly or moderately' bound alpha-chymotrypsins against irr
eversible thermal inactivation but are without effect on the stability
of 'rigidly' bound enzyme.