Vitamin K contents in liver tissue of hepatocellular carcinoma patients.

Serum protein induced in vitamin K absence-II (PIVKA-II) is used as a tumor marker because it increases at a notably higher rate in patients with hepatocellular carcinoma. To clarify the mechanism causing the elevation of serum PIVKA-II, we measured the contents of vitamins K1 (phylloquinone, PK) and K2 (menaquinone, MK) (MK-4, MK-5, MK-6, MK-7, MK-8, MK-9, MK-10) in liver tissue resected from 21 hepatic cancer patients (12 patients with hepatocellular carcinoma and 9 patients with metastatic hepatic cancer), using HPLC combined with coulometric reduction and fluorometric detection. In the cancerous tissue of hepatocellular carcinoma patients, PK, MK-7, MK-8, and MK-10 were significantly lower than that found in the noncancerous tissue. Furthermore, MK-6, MK-7, MK-8, and MK-10 in the cancerous tissue of hepatocellular carcinoma patients were significantly lower than that in the cancerous tissue of metastatic hepatic cancer patients. These data suggested that one of the mechanisms of the elevation of serum PIVKA-II levels in hepatocellular carcinoma patients is a vitamin K deficiency in the local cancerous tissue.

Recruitment of a foreign quinone into the A(1) site of photosystem I. I. Genetic and physiological characterization of phylloquinone biosynthetic pathway mutants in Synechocystis sp. pcc 6803.

Genes encoding enzymes of the biosynthetic pathway leading to phylloquinone, the secondary electron acceptor of photosystem (PS) I, were identified in Synechocystis sp. PCC 6803 by comparison with genes encoding enzymes of the menaquinone biosynthetic pathway in Escherichia coli. Targeted inactivation of the menA and menB genes, which code for phytyl transferase and 1,4-dihydroxy-2-naphthoate synthase, respectively, prevented the synthesis of phylloquinone, thereby confirming the participation of these two gene products in the biosynthetic pathway. The menA and menB mutants grow photoautotrophically under low light conditions (20 microE m(-2) s(-1)), with doubling times twice that of the wild type, but they are unable to grow under high light conditions (120 microE m(-2) s(-1)). The menA and menB mutants grow photoheterotrophically on media supplemented with glucose under low light conditions, with doubling times similar to that of the wild type, but they are unable to grow under high light conditions unless atrazine is present to inhibit PS II activity. The level of active PS II per cell in the menA and menB mutant strains is identical to that of the wild type, but the level of active PS I is about 50-60% that of the wild type as assayed by low temperature fluorescence, P700 photoactivity, and electron transfer rates. PS I complexes isolated from the menA and menB mutant strains contain the full complement of polypeptides, show photoreduction of F(A) and F(B) at 15 K, and support 82-84% of the wild type rate of electron transfer from cytochrome c(6) to flavodoxin. HPLC analyses show high levels of plastoquinone-9 in PS I complexes from the menA and menB mutants but not from the wild type. We propose that in the absence of phylloquinone, PS I recruits plastoquinone-9 into the A(1) site, where it functions as an efficient cofactor in electron transfer from A(0) to the iron-sulfur clusters.