Biomaterial Database

Effect of pH changes on the binding of vitamin B12 by intrinsic factor. 1971

H Y Shum, and B J O'Neill, and A M Streeter

The binding of vitamin B(12) by human gastric juice has been found to be pH dependent. Maximum binding occurs between pH 6.5 and 10. Outside this pH range the vitamin B(12)-binding ability of human gastric juice decreases and at pH below 2 or above 12.2 this drops sharply to about 10 to 15% of the maximum. Three commercial hog intrinsic factors have been found to give a similar response to pH changes. The pH-dependent binder in human gastric juice has been shown to be intrinsic factor by the addition of intrinsic factor-blocking antibody. About 10% of vitamin B(12) bound by human gastric juice is not bound by intrinsic factor and is not pH dependent. The reduction in the vitamin B(12)-binding capacity of human gastric juice induced by an adverse pH is reversed by neutralization. The physiological and clinical significance of these observations is discussed and their relevance to various procedures in vitro noted.

UI	MeSH Term	Description	Entries
D007437	Intrinsic Factor	A glycoprotein secreted by the cells of the GASTRIC GLANDS that is required for the absorption of VITAMIN B 12 (cyanocobalamin). Deficiency of intrinsic factor leads to VITAMIN B 12 DEFICIENCY and ANEMIA, PERNICIOUS.	Factor, Intrinsic
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D002606	Charcoal	An amorphous form of carbon prepared from the incomplete combustion of animal or vegetable matter, e.g., wood. The activated form of charcoal is used in the treatment of poisoning. (Grant & Hackh's Chemical Dictionary, 5th ed)	Activated Charcoal,Actidose,Actidose-Aqua,Adsorba,Carbomix,Charbon,CharcoAid,CharcoCaps,Charcodote,Formocarbine,Insta-Char,Kohle-Compretten,Kohle-Hevert,Kohle-Pulvis,Kohle-Tabletten Boxo-Pharm,Liqui-Char,Norit,Ultracarbon,Charcoal, Activated
D003036	Cobalt Isotopes	Stable cobalt atoms that have the same atomic number as the element cobalt, but differ in atomic weight. Co-59 is a stable cobalt isotope.	Isotopes, Cobalt
D005750	Gastric Juice	The liquid secretion of the stomach mucosa consisting of hydrochloric acid (GASTRIC ACID); PEPSINOGENS; INTRINSIC FACTOR; GASTRIN; MUCUS; and the bicarbonate ion (BICARBONATES). (From Best & Taylor's Physiological Basis of Medical Practice, 12th ed, p651)	Gastric Juices,Juice, Gastric,Juices, Gastric
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D000906	Antibodies	Immunoglobulin molecules having a specific amino acid sequence by virtue of which they interact only with the ANTIGEN (or a very similar shape) that induced their synthesis in cells of the lymphoid series (especially PLASMA CELLS).
D012709	Serum Albumin	A major protein in the BLOOD. It is important in maintaining the colloidal osmotic pressure and transporting large organic molecules.	Plasma Albumin,Albumin, Serum