ABSTRACT
Owing to the lack of sensitivity and/or selectivity of the existing chemical assays, vitamin K deficiency has always been diagnosed indirectly by measuring its effect on blood coagulation. We used our recently developed multidimensional liquid chromatographic assay for what is, to the best of our knowledge, the first systematic investigation of physiological vitamin K levels in human blood. It allowed the unequivocal demonstration of trans-phylloquinone (vitamin K1) and its quantification down to a level of 0.5 nanogram per milliliter of serum (ng/ml. In healthy adults, a mean serum concentration of 2.6 ng/ml was found, with a normal range of 0.9 to 7.8 ng/ml. These values apparently are distributed in a log-normal way.
Subject(s)
Vitamin K Deficiency/blood , Vitamin K/blood , Adult , Chromatography, High Pressure Liquid/methods , Fasting , Humans , Reference ValuesABSTRACT
A temperature-sensitive mutant having a lethal mutation in the gene for the beta subunit of RNA polymerase (nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) exhibits an apparent 2- to 3-fold decrease in the rates of both beta and beta' subunit synthesis at the non-permissive temperature, relative to total protein. In contrast, a temperature-sensitive mutant with a lethal mutation in the gene encoding beta' has a 5- to 6-fold increase in the rates of beta and beta' synthesis at 42 degrees. These beta and beta' mutants also exhibit rapid degradation of both subunits at the high temperature.
