TY - JOUR
T1 - Vitamin B12 bioavailability from egg yolk and egg white
T2 - Relationship to binding proteins
AU - Levine, A. S.
AU - Doscherholmen, A.
PY - 1983
Y1 - 1983
N2 - Egg yolk has been reported to inhibit B12 absorption less than egg white suggesting that different vitamin B12 binding proteins may be present in egg white and egg yolk. Using gel-exclusion chromatography we found that the mean M(R) for the B12 binding protein derived from egg yolk was 125,000, whereas that derived from egg white was 97,750. Heat treatment of the apoprotein differentially reduced the binding capacity of egg yolk and egg white in a time-dependent manner with the greatest decrease in binding capacity occurring with egg white. In contrast, heat treatment of the haloenzyme delineated the egg yolk as the more labile. These studies suggest that egg yolk and egg white contain distinct R binders which could explain the differential B12 absorption from egg yolk and egg white.
AB - Egg yolk has been reported to inhibit B12 absorption less than egg white suggesting that different vitamin B12 binding proteins may be present in egg white and egg yolk. Using gel-exclusion chromatography we found that the mean M(R) for the B12 binding protein derived from egg yolk was 125,000, whereas that derived from egg white was 97,750. Heat treatment of the apoprotein differentially reduced the binding capacity of egg yolk and egg white in a time-dependent manner with the greatest decrease in binding capacity occurring with egg white. In contrast, heat treatment of the haloenzyme delineated the egg yolk as the more labile. These studies suggest that egg yolk and egg white contain distinct R binders which could explain the differential B12 absorption from egg yolk and egg white.
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U2 - 10.1093/ajcn/38.3.436
DO - 10.1093/ajcn/38.3.436
M3 - Article
C2 - 6684393
AN - SCOPUS:0020643062
SN - 0002-9165
VL - 38
SP - 436
EP - 439
JO - American Journal of Clinical Nutrition
JF - American Journal of Clinical Nutrition
IS - 3
ER -