25-Hydroxylation of vitamin D2 and D3 was studied in subcellular fractions from human liver, using a technique based on isotope dilution-mass spectrometry. The mitochondrial fraction fortified with isocitrate catalysed 25-hydroxylation of vitamin D3 at a rate of about 10 pmol/mg protein X min. Under the same conditions, the rate of 25-hydroxylation of vitamin D2 was less than 2 pmol/mg protein X min. Crude microsomes fortified with NADPH catalysed 25-hydroxylation of vitamin D3 to a very low extent, and this activity was not linear with the amount of microsomal protein. A higher rate of conversion was obtained with a partially purified cytochrome P-450 fraction in the presence of NADPH-cytochrome P-450 reductase and NADPH. This fraction also catalysed 25-hydroxylation of 1 alpha-hydroxyvitamin D3 and 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha-triol. 25-Hydroxylation of vitamin D2 could not be detected, neither with crude microsomes, nor with the microsomal cytochrome P-450 fraction. Since the assay for 25-hydroxyvitamin D2 was less sensitive than that for 25-hydroxyvitamin D3, these experiments do not rule out the presence of some 25-hydroxylase activity towards vitamin D2 in the microsomes. The results are discussed in relation to previous work in which a lower toxicity has been reported for vitamin D2 than for vitamin D3 in some mammalian species.
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http://dx.doi.org/10.3109/00365518609084051 | DOI Listing |
Enzyme Microb Technol
December 2024
College of Biomass Science and Engineering, Sichuan University, Chengdu 610065, China.
Calcidiol (25(OH)VD) and calcitriol (1α,25(OH)VD) are active vitamin D with high medicinal value, which can maintain calcium and phosphorus balance and treat vitamin D deficiency. Microbial synthesis is an important method to produce high-value-added compounds. It can produce active vitamin D through the hydroxylation reaction of P450, which can reduce the traditional chemical synthesis steps, and greatly improve the production efficiency and economic benefits.
View Article and Find Full Text PDFFront Physiol
September 2024
Department of Poultry Science, University of Georgia, Athens, GA, United States.
Appl Microbiol Biotechnol
July 2024
Research Group BIONUC (Biotechnology of Nutraceuticals and Bioactive Compounds), Departamento de Biología Funcional, Principality of Asturias, Área de Microbiología, Universidad de Oviedo, Oviedo, Spain.
Vitamin D deficiencies are linked to multiple human diseases. Optimizing its synthesis, physicochemical properties, and delivery systems while minimizing side effects is of clinical relevance and is of great medical and industrial interest. Biotechnological techniques may render new modified forms of vitamin D that may exhibit improved absorption, stability, or targeted physiological effects.
View Article and Find Full Text PDFBiofactors
October 2024
Aix-Marseille Université, C2VN, INRAE, INSERM, Marseille, France.
Aging and obesity are associated with a decrease in plasma 25-hydroxyvitamin D (25(OH)D) levels. In the context of a growing aging population and the rising incidence of obesity, we hypothesized that aging process, either independently or in combination with obesity, could influence vitamin D (VD) metabolism, consequently resulting in the reduced 25(OH)D plasma concentrations. C57BL/6JRJ young (6 months) and old (23 months) mice fed with control (CD) or high fat diet (HF) were compared.
View Article and Find Full Text PDFBest Pract Res Clin Endocrinol Metab
March 2024
Department of Endocrinology, Seth G S Medical College and King Edward Hospital, Mumbai 400012, India.
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