Article Abstract:
The critical sites for protein thermostabilization by proline substitution in oligo-1,6-glucosidase from Bacillus coagulans are Lys-121, Glu-290, Lys-457 and Glu-487. Mutations of the enzyme that increase stability are those that support the proline rule of substituting neutral residues with proline residues for stability. A comparison of the enzyme from B. coagulans with that from B. cereus and B. thermoglucosidasius indicates that the primary structures have many similarities despite differences in thermostability. Thermostability increases with the number of prolines in the enzymes.
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Article Abstract:
The heat resistance of native and demineralized spores of Bacillus subtilis STCC 4525 strain sporulated at 32 and 52 degrees C in citrate-phosphate buffer of pH 7 and 4 has been studied. The bacterial strain was isolated during a routine inspection on the sterility of canned asparagus. Spore demineralization was carried out by acid titration with HCl and incubation for 14 hours at 60 degrees C. Results indicate demineralization weakened the heat resistance of B. subtilis spores but the reduction was dependent on sporulation temperature and heating menstruum pH.
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Article Abstract:
The profile of the survival curves of Bacillus coagulans STCC 4522 sporulated at 52 degrees C, at various heating temperatures was investigated, with emphasis on the early moments of treatment. A highly heat-sensitive spore subpopulation that includes more than 90% of the total spore population was observed. This heat-sensitive spore was inactivated after two seconds of treatment at 111 degrees C.
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