Factors affecting the binding of cyanocobalamin to serum proteins from various animals

A Comparison of the Properties of Chicken Serum with Other Vitamin B12 Binding Proteins Used in Radioisotope Dilution Methods for Measuring Serum Vitamin B12 Concentrations

“…berg & Fudenberg, 1969;Shum et a?, 1971)~ as confirmed in this study (Fig I), whereas others disagree (McGuigan, 1967;Rose, 1971). With NS our finding is in general agreement with all others that the B,,-binding capacity is greatly reduced when the pH is around 3.5 (Miller & Sullivan, 1959;Rosenthal et al, 1962;Meyer, 1965) but only the results of Meyer (1965) are confirmed by our observation of decreasing binding as the pH falls from 9.0 to 5.5 (Fig I). Our finding that the B12-binding capacity of CMLS is reduced at pH 3.5 (Fig I) is at variance with that of Miller & Sullivan (1959).…”

“…Our finding that the B12-binding capacity of CMLS is reduced at pH 3.5 (Fig I) is at variance with that of Miller & Sullivan (1959). In the case of CS the only data that existed on the effects of pH or I o n its B,,-binding capacity at the time when we initiated our study were included in a paper of Rosenthal et a? (1962).…”

A simple and fast extraction method for organochlorine pesticides and polychlorinated biphenyls in small volumes of avian serum

“…Urea, which has a dipole-moment, denatures (unfolds) proteins by disrupting the intramolecular electrostatic interactions. Urea has also been reported to eliminate the binding of Vitamin B 12 (cyanocobalamin) to human, dog, and rabbit serum [14] and to interfere with the binding of antithyroid drugs with serum albumin [15]. The effects of urea on proteins are mild and often reversible as shown by restoration of more than 90% activity of a urea-denatured eclosion hormone [16].…”