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Serum Vitamin B 12 Binding Proteins in Viral Hepatitis
Author(s) -
Rachmilewitzy M.,
Moshkowitz B.,
Rachmilewitz B.,
Grossowicz N.,
Gross J.
Publication year - 1972
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1111/j.1365-2362.1972.tb00650.x
Subject(s) - vitamin b , hepatitis b , chemistry , peptide , vitamin , hepatitis b virus , binding site , biochemistry , biology , immunology , virus
. Sera from patients with viral hepatitis were examined for serum vitamin B 12 concentration, unsaturated B 12 binding capacity, total B 12 binding capacity of whole serum and of separate transcobalamin‐I and transcobalamin‐II fractions. It was found that the high serum B 12 concentrations observed were associated with an increase in the B 12 binding of the transcobalamins. The B 12 bound to transcobalamin‐I was found to be two to three times higher than that in normal subjects. The most striking difference was the finding of excessive amounts of B 12 bound to transcobalamin‐II, as much as 30 to 40 times the normal. The unsaturated B 12 binding capacity of hepatitis sera is usually very low. In addition to the B 12 bound to transcobalamins, a considerable part of the elevated serum B 12 in hepatitis was in a dialyzable form and was not bound to either transcobalamin‐I or transcobalamin‐II. This dialyzable B 12 is apparently bound to a small peptide (M.W less than 10000) which permits its passage through dialysis membrane but makes the B 12 molecule unavailable to the microorganism in the bioassay, unless it is released from the peptide complex by boiling.