ISSN:
1573-4927
Keywords:
β-glucuronidase
;
heat stability
;
regulation of synthesis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract The enzymes coded for by two alleles at the glucuronidase structural locus (Gus) were compared in their response to pH, buffering anion, buffer molarity, ionic strength, and temperature. The heat-labile Gush gene product responded in a qualitatively similar but quantitatively reduced manner compared to the relatively heat-stable Gus b gene product. In all buffers tested, the enzyme was most heat stable at pH 5.0. Ranking of the various buffer anions tested, according to increasing heat stabilization, was water ≪ acetate ≤ phosphate 〈 citrate. Varying the molarity of the buffers from 0.01 to 0.6 m at pH 5.0 revealed further differences among the buffers. Increasing ionic strength exerted a destabilizing force on the protein. The half-life of the enzyme decreased by as much as a hundredfold between 71 and 75 C. The Gush/Gush genotype also results in decreased activity levels in all tissues, reportedly because of decreased synthesis. The heat inactivation curves of Gusb/Gush heterozygotes were incompatible with any theoretical curve based on the assumption that the Gusb and Gush chromosomes in the heterozygote behave in a manner similar to that seen in the homozygotes.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00484095
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