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|Title:||Effect of gastrointestinal proteases on purified human intrinsic factor-vitamin B<sub>12</sub> (IF-B<sub>12</sub>) complex|
|Abstract:||Intrinsic factor (IF) from human gastric juice was purified and complexed with vitamin B<sub>12</sub> (IF-B<sub>12</sub> complex) on Sepharose-vitamin B<sub>12</sub> affinity matrix. By labeling studies, using [<sup>57</sup>Co] vitamin B<sub>12</sub> and <sup>125</sup>I, the specific B<sub>12</sub> binding activity of IF was found to be 23 μgB<sub>12</sub>/mg protein, and the molecular size by gel filtration 60 kDa. Proteolysis of the IF-B<sub>12</sub> complex by sequential treatment with pepsin, trypsin, α-chymotrypsin and carboxypeptidase A, followed by chromatography of proteolysed complex and IF-B<sub>12</sub> showed higher mobility of proteolysed fraction. Gel filtration, however, showed same molecular size for both proteolysed and the IF-B<sub>12</sub> complex. On SDS-PAGE, purified IF-B<sub>12</sub> appeared as a single band of 60 kDa. The proteolysed complex had higher mobility on SDS-PAGE and did not bind to zirconium phosphate gel. Immunodiffusion with rabbit antisera had positive reaction with IF-B<sub>12</sub>, but there was no reaction with the proteolysed sample.|
|Appears in Collections:||IJBB Vol.40(2) [April 2003]|
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