This paper presents the results of assays for antihemorrhagic activity carried out on an array of naphthoquinones and related compounds synthesized as described in a series of previous papers. Some of the compounds were prepared as synthetic models of the structural types postulat.ed (1) for vitamins K1 and Kz (l-5); others were synthesized subsequent to the establishment of the structure of vi...

Introduction : Two types of vitamin K occur in nature: vitamin K1 (phylloquinone, 2-methyl-3-phytyl-1,4-naphthoquinone), which is derived from plants, and vitamin K2 (menaquinones), a series of vitamers with multiisoprene units at the 3-position. Vitamin K2 activates osteoblasts to enhance calcification, acts as a coenzyme of γ-carboxylase for the Gla protein, and is also reported to inhibit bo...

A sensitive method for the determination of vitamin K1(20) in serum microsamples (50 microL) has been developed, utilizing solid-phase extraction with C8 Bond-Elut columns and reversed-phase narrow-bore high-performance liquid chromatography [2.1 mm (i.d.), column] with a nonaqueous eluent. Recovery from serum (49 ng/mL) was 76% (n = 2). Peak homogeneity was assessed by photodiode array detecti...

We aimed to confirm the correlations between rs2359612 and rs9923231 single nucleotide polymorphisms (SNPs) in the vitamin K epoxide reductase complex subunit 1 (VKORC1) gene and the risk of cardiovascular and cerebrovascular diseases (CCVDs) using meta-analysis. Electronic databases were exhaustively searched for relevant case-control studies by employing stringent inclusion and exclusion crit...

since measurements of O2 uptake with intact bacteriaor extracts indicated approximately the same ratio of activities. Further, bacteria growing on D(-)-mandelate did not accumulate benzaldehyde, which shows that D(-)-mandelate dehydrogenase, rather than benzaldehyde dehydrogenase I (Cook et al., 1975), was now rate-limiting. D(-)-Mandelate dehydrogenase resembles L(+)-mandelate dehydrogenase in...

Previously, vitamin K was recognized solely as a cofactor for blood clotting. However, the discovery of vitamin K-dependent proteins (VKDPs) led to a more comprehensive understanding of vitamin K’s role with respect to bone and cardiovascular health. Research has demonstrated that high intakes of vitamin K2 (but not K1), through its activation of the VKDP Matrix Gla Protein (MGP), is associated...

Protein disulfide bond formation contributes to the folding and activity of many exported proteins in bacteria. However, information about disulfide bond formation is limited to only a few bacterial species. We used a multifaceted bioinformatic approach to assess the capacity for disulfide bond formation across this biologically diverse group of organisms. We combined data from a cysteine count...