The sources of the vitamines

Retinyl esters are a major endogenous storage source of vitamin A in vertebrates and their hydrolysis to retinol is a key step in the regulation of the supply of retinoids to all tissues. Some members of nonspecific carboxylesterase family (EC 3.1.1.1) have been shown to hydrolyze retinyl esters.However, the number of different isoenzymes that are expressed in the liver and their retinyl palmitate hydrolase activity is not known.

12p research12 23-04-2013 36 5   Download

Intrinsic factor (IF) is the gastric protein that promotes the intestinal uptake of vitamin B12 . Gastric IF from animal sources is used in diagnostic tests and in vitamin pills. However, administration of animal IF to humans becomes disadvantageous because of possible pathogenic transmis-sion and contamination by other B12binders. We tested the use of recombinant plants for large-scale production of pathogen-free human recombinant IF. Human IF was successfully expressed in the recombinant plantArabidopsis thaliana....

6p tumor12 20-04-2013 37 3   Download

The cone snail is the only invertebrate system in which the vitamin K-dependent carboxylase (orc-carboxylase) and its product c-carboxygluta-mic acid (Gla) have been identified. It remains the sole source of structural information of invertebrate c-carboxylase substrates. Four novel Gla-con-taining peptides were purified from the venom of Conus textileand charac-terized using biochemical methods and mass spectrometry.

10p dell39 27-03-2013 41 3   Download

During anaerobic cobalamin (vitamin B12) biosynthesis, CbiL catalyzes methylation at the C-20 position of a cyclic tetrapyrrole ring usingS-aden-osylmethionine as a methyl group source. This methylation is a key modifi-cation for the ring contraction process, by which a porphyrin-type tetrapyrrole ring is converted to a corrin ring through elimination of the modified C-20 and direct bonding of C-1 to C-19.

11p inspiron33 23-03-2013 35 2   Download

The metabolic pathways leading froml-[2-13 C]aspartic acid, [2-13 C]glycine andl-[methyl-13 C]methionine to vitamin B12were investigated, focusing on the biosynthetic pathways leading to the aminopropanol moiety of vita-min B12and on the role of the Shemin pathway leading tod-aminolevulinic acid (a biosynthetic intermediate of tetrapyrrole), by means of feeding experiments with Propionibacterium shermaniiin combination with 13 C-NMR spectroscopy.

6p media19 04-03-2013 33 1   Download