Potent inhibitory effects of the 5'-triphosphates of (E)-5-(2-bromovinyl)-2'-deoxyuridine and (E)-5-(2-bromovinyl)-1-beta-D-arabinofuranosyluracil on DNA polymerase gamma

(E)-5-(2-Bromovinyl)-2'-deoxyuridine 5'-triphosphate (BrVdUTP) and (E)-5-(2-bromovinyl)-1-beta-D-arabinofuranosyluracil 5'-triphosphate (BrVarafUTP), which are known as specific inhibitors of herpes simplex viral (type 1 and 2) DNA polymerase, were found to be strong inhibitors of DNA polymerase gamma from human KB and murine myeloma cells. In fact BrVdUTP and BrVarafUTP were found to be stronger inhibitors of DNA polymerase gamma than of other DNA polymerases having viral (herpes simplex virus or retrovirus) origin or cellular (eukaryotic alpha and beta, or prokaryotic) origin. The mode of inhibition of DNA polymerase gamma by BrVdUTP and BrVarafUTP was competitive with respect to dTTP, the normal substrate. Whereas BrVdUTP was an efficient substrate for DNA polymerase gamma and other DNA polymerases that were examined, BrVarafUTP failed to serve as a substrate for DNA synthesis. Ki values for BrVdUTP (40 nM) and BrVarafUTP (7 nM) with DNA polymerase gamma, as determined with (rA)n.(dT) as the template.primer, were much smaller than the Km values for dTTP (0.16 microM and 0.71 microM for murine and human DNA polymerase gamma, respectively). Thus, the affinity of BrVdUTP or BrVarafUTP for DNA polymerase gamma was much stronger than that of dTTP.     

Isolation and characterization of a fatty acyl esterase from rat lung

In an effort to facilitate studies of the reaction involved in the removal of fatty acids from acyl proteins, we have synthesized an octanoic acid ester of doubly blocked serine, specifically octanoyl N-carbobenzoxy-L-serine-benzyl ester (octanoyl boc-serine), and used it as a substrate to guide the purification of an esterase from rat lung. The esterase was purified 228-fold by column chromatography on DE-52 cellulose, hydroxylapatite, octyl-Sepharose, and concanavalin A-Sepharose and by HPLC gel filtration. The final enzyme preparation ran as a single 77,000-Da band when subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and exhibited a single symmetrical peak (sedimentation coefficient, 4.5 S) when centrifuged through a sucrose density gradient (empirical Mr, 63,000). The esterase is an acidic protein, pI 4.1, and is very active against p-nitrophenyl esters comprised of C4-C14 fatty acids; the highest specific activity (26.5 mumol/min/mg) was obtained using p-nitrophenyl caprylate as substrate. The pH optimum of the lung esterase is near 8.0 and the activity on octanoyl boc-serine is maximum when 0.3% (w/v) Myrj-52 is included in the assay medium. The activity of the esterase is not dependent on calcium ions. The enzyme does not remove acyl groups from the G-protein of vesicular stomatitis virus or the proteolipid of bovine brain. The possible role of the esterase in the metabolism of acylated proteins is considered.     

A study of connective tissue macromolecules in skin of mice with goldthioglucose-induced obesity.

The effect of obesity on the connective tissue composition of skin was investigated in mice with goldthioglucose (GTG)-induced obesity. Four months after GTG treatment, the obese animals were sacrificed. Acid mucopolysaccharides, glycoproteins, collagen, and elastin were analyzed in the skin and compared to the controls. Total MPS in the skin from obese animals decreased, reflected mostly in hyaluronic acid. Chondroitin showed an increase over controls. The content of soluble glycoproteins varied; total carbohydrate and sialic acid of the glycoprotein tended to increase with obesity. Collagen and elastin both tended to decrease with obesity.