BIOT 139 |
| Reducing the moisture content of crystalline Apo2L/TRAIL, a non-covalent homotrimer, below 5% may decrease the stability of the protein, a result significantly different than observed for proteins lyophilized in a glassy state. The primary degradation product at low moisture content is one that does not occur in solution or in non-crystalline lyophilized formulations. A concurrent increase in hexamer content by native SEC and non-reducible dimer under denaturing conditions suggests that the degradation product is a non-disulfide, covalent bond between monomers in adjacent trimers. This is further supported by the apparent ratio of one covalent dimer to four monomers in purified hexamer. Increasing the residual moisture can decrease the formation rate of this covalent hexamer but increase the rate of intramolecular disulfide bonds within the trimer. Further investigation into the degradation mechanisms of Apo2L/TRAIL crystals is ongoing. |
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Biophysical and Biomolecular Symposium: Protein Chemical Instability
8:00 AM-11:05 AM, Tuesday, August 21, 2007 BCEC -- 106, Oral
Division of Biochemical Technology |