Interaction of flavodoxin with cobalamin-dependent methionine synthase.

Cobalamin-dependent methionine synthase catalyzes the transfer of a methyl group from methyltetrahydrofolate to homocysteine, forming tetrahydrofolate and methionine. The Escherichia coli enzyme, like its mammalian homologue, is occasionally inactivated by oxidation of the cofactor to cob(II)alamin. To return to the catalytic cycle, the cob(II)alamin forms of both the bacterial and mammalian enzymes must be reductively remethylated.

Mouse apolipoprotein J: characterization of a gene implicated in atherosclerosis.

Apolipoprotein J (apoJ), a glycoprotein associated with subclasses of plasma high density lipoproteins (HDL), was found to accumulate in aortic lesions in a human subject with transplantation-associated arteriosclerosis and in mice fed a high-fat atherogenic diet. Foam cells present in mouse aortic valve lesions expressed apoJ mRNA, suggesting local synthesis contributes to apoJ's localization in atherosclerotic plaque. As a prerequisite for elucidating the physiological function of apoJ by using a mouse model, cDNA clones representing the mouse homolog of apoJ were isolated, characterized, and sequenced.

Apolipoprotein J is associated with paraoxonase in human plasma.

Apolipoprotein J (apoJ)-containing high-density lipoproteins (HDL), isolated from human plasma by immunoaffinity chromatography, are associated with apoAI and a protein of approximately 44 kDa. In order to advance our understanding of apoJ's role in the vasculature, a comprehensive investigation was performed to identify and characterize this 44-kDa protein and to study its interaction with apoJ. The 44-kDa protein, a monomeric glycoyslated polypeptide, was identified by N-terminal sequencing as serum paraoxonase.

Role of cysteine residues in Pseudomonas mevalonii 3-hydroxy-3-methylglutaryl-CoA reductase. Site-directed mutagenesis and characterization of the mutant enzymes.

Each of the four identical subunits of Pseudomonas mevalonii 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase contains two cysteine residues, Cys156 and Cys296 (Beach, M. J., and Rodwell, V.