Bacillus thermoglucosidius α-Glucosidase: Temperature Dependence of Activity and Stability1

Abstract

A p-nitrophenyl-alpha-D-glucopyranoside-hydrolyzing alpha-glucosidase from an obligate thermophile, Bacillus thermoglucosidius KP 1006, gave a triphasic relationship at pH 6.8 in the van't Hoff plot of Km, in the Arrhenius plot of the first order rate constant of inactivation with 0.1% sodium dodecyl sulfate, and in the logarithmic plot of the maximal fluorescence intensity at 346 nm versus reciprocal of temperature. The respective plots exhibited two breaks at 40 and 61 degrees C, 43 and 62 degrees C, and 40 and 61 degrees C. However, the Arrhenius plot of the molecular activity at pH 6.8 had a single discontinuity at 64 degrees C. These findings, together with thermodynamic quantities for the enzyme, suggest that the thermal conformation changes in the enzyme protein occur around 40--43 degrees C and 61--64 degrees C. The Arrhenius plot of the rate constant of heat inactivation at pH 6.8 was bent at 73 degrees C. Thermodynamic data indicate that the enzyme is transformed from a heat stable form into a heat unstable form at 73 degrees C with temperature elevation. The critical points localized near the minimum, optimum, and maximum temperatures (40, 60, and 72 degrees C) of the cell growth, respectively.

Investigation of metabolite changes in the transition from pre‐invasive to invasive cervical cancer measured using 1H and 31P magic angle spinning MRS of intact tissue

“…An alternative explanation is that the type of CIN that progresses to cancer is metabolically different from CIN that does not show this progression. An increase in PC concentrations has been shown in immortalised Schwann cells virally transfected with oncogenes SV40 (24), and specific enzyme activities in phosphatidylcholine synthesis are increased in virally infected cells compared with control cells (24,25). In the development of invasive cervical cancer, genomic integration of oncogenic human papillomavirus appears to be an important genetic event (26); two viral proteins, E6 and E7, alter cell cycle control and are implicated in human papillomavirus-induced oncogenesis (27).…”

Formulation of proteins and monoclonal antibodies (mAbs)

“…Although there may be several different unfolded forms, these different forms will all be inactive and not distinguishable from each other by activity assays. In the case of the enzyme α-glucosidase isolated from the bacterial thermophile Bacillus thermoglucosidius, the incorporation of a reversible and irreversible pathway into the kinetic model resulted in linear Arrhenius plots for the rate constants for each process (Suzuki, Nakamura, Kishigami, & Abe, 1980;Yoshioka, Izutsu, Aso, & Takeda, 1991).…”

Purification and Properties of a Thermostable Inulinase (β-D-Fructan Fructohydrolase) fromBacillus stearothermophilus KP1289

“…4A)]. Arrhenius plots of ν values of fructose release [23] showed that the apparent activation energy (at pH 5.0) was 160 kJ/mol at 30-40°C and 32 kJ/mol at 40-60°C. The enzyme was stable up to 60°C for 10 min at pH 7.0 (Fig.…”