Vitamin labeling methods

This method has been applied to analyses as different as the determination of vitamin B12 in biological tissue (using a 60Co label), and the amount of hydrogen absorbed into the lattice of a transition metal. 

JW DeVries. Water-soluble vitamins. In DM Sullivan, DE Carpenter, eds. Methods of Analysis for Nutritional Labelling. Arlington, VA AOAC International, 1993, pp 131-135. 

The low-molecular-weight vitamin biotin is easily conjugated to antibodies and enzyme markers. Up to 150 biotin molecules can be attached to one antibody molecule, and the strong affinity of the biotin for the glycoprotein avidin allows its use as complex-ing secondary reagents. Biotin labeling of the primary (direct) or secondary (indirect) antibody can be used in the avidin-biotin methods. In the labeled avidin method the tracer is attached directly to the avidin molecule. In the avidin-biotin bridge method a biotinylated enzyme such as peroxidase is allowed to bind after attachment of avidin to the biotin-labeled antibody. 

Most biochemical methods are based on the assimilation of CO2 by plants and the feeding of various kinds of microorganisms or animals with labelled compounds. Afterwards, the compounds synthesized in the plants, microorganisms or animals are isolated. In this way, glucose, amino acids, adenosine triphosphate, proteins, alkaloids, antibiotics, vitamins and hormones can be obtained that are labelled with or Cultures of various microorganisms such as clorella vulgaris may be applied and operated as radionuclide farms . The labelled compounds produced by biochemical methods are, in general, labelled at random, i.e. not at special positions. 

After Underwood wondered in 1977 whether we could use kinetic methods to estimate vitamin A disposal rate in the rat, we collaborated on an in vivo kinetic experiment in vitamin A-deficient and control rats (Lewis et al, 1981). We measured plasma [ HJvitamin A disappearance for 48 hr after intravenous administration of pH]retinol-labeled plasma and used graphical methods to calculate vitamin A disposal rate. The results sug-... 

The purpose of this paper is to give a brief survey on syntheses and chemical transformations of vitamin E. Special emphasis will be laid on methods suitable for labeling of the tocopherols. Except for a-, jS-, 7-, and 6-tocopherol, the tocol nomenclature proposed by Karrer and Fritzsche (1938) will be used throughout this review. 

The nickel-containing factor F 430 (134) provides an example of how nature exploits the reactivity of organometallic compounds, as is the case with vitamin B12. Factor F 430 (134) plays a key role as cofactor for the coenzyme M reductase of primitive methanogenic bacteria in the formation of methane from 2-(methylthio)-ethanesulfonate (86). The structural elucidation of factor F 430 (134) is based on a combination of classical spectroscopic methods, chemical degradation, and biosynthetic studies with C-labelled precursors 83a,b). These biosynthetic investigations will be addressed in section 8.2. Chemical degradation products obtained by ozonolysis of factor F 430 (134) allowed the determination of the absolute configuration by comparison with reference compounds derived from chlorophyll a (2) and vitamin B12 (4) 83a,b). 

The ASBC describe such a method. Some representative values for British beers are given in Table 22.21 where the results are also expressed in kilojoules (1 kcal = 4 184 kJ). Many brewers of low carbohydrate lite beers declare the calorific value (e.g. 26-29 kcal/100 ml) on the label. Beer is also a source of B vitamins containing (values in ppb for lagers and top fermentation beers) biotin (7-18 11-12), nicotinic acid (4494-8607 7500-7753), pantothenic acid (1093-1535 1375-1808), pyridoxine (329-709 341-546), riboflavin (219-420 331-575), and thiamine (15-58 59-181) [117]. Folic acid and vitamin Bj are also present [10]. 

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