Amounts Of Avidin Research Articles

Dietary Biotin Deficiency Affects Reproductive Function and Prenatal Development in Hamsters

The effects of maternal dietary biotin deficiency on hamster embryos were examined by adding different amounts of avidin (0, 10, 50, 100 or 1000 mg/kg diet) to a semipurified commercial diet during the entire period of gestation. On d 10 of gestation, reduced dietary biotin resulted in a high incidence of resorbed and dead embryos. In addition, both the crown-rump length and head length of dietary biotin-deficient embryos were lower, and their digit development was retarded. These embryos were characterized by pericardial cavity enlargement (40%) and zig-zag closure line of the neural tube (44%). Some embryos exhibited abnormalities of the craniofacial region and tail. On d 14 of gestation, embryonic growth retardation, morphological abnormalities and skeletal defects were seen in the dietary biotin-deficient group (fed 100 mg avidin/kg diet). The striking abnormalities were cleft palate, micromelia, micrognathia and rib deformities in approximately 10% of the fetuses. Histological examination of the placentae revealed some differences in the spongiotrophoblast and labyrinth layers between the control and dietary biotin-deficient groups. The teratogenic effect of dietary biotin deficiency previously observed in mice was confirmed in hamsters.

Homogeneous enzyme-linked competitive binding assay for biotin based on the avidin-biotin interaction

A homogeneous enzyme-linked competitive-binding assay for biotin with glucose-6-phosphate dehydrogenase (G6PDH), is described. This assay is based on the interaction between a G6PDH/biotin conjugate with avidin, a natural binder for biotin. In the absence of biotin in the assay mixture, this interaction results in 100% inhibition of the enzyme conjugate. In the presence of biotin, the enzymatic activity of the conjugate is regained in an amount related to the concentration of the vitamin in the sample. Extremely steep, gate-like dose/response curves, attributable to the relative binding affinities of avidin for biotin and the conjugate, are observed. The detection limits of the system vary with the amounts of avidin and enzyme/biotin conjugate used. The method is rapid and sensitive and is evaluated for the direct determination of biotin in vitamin tablets.