Anti-viral activity of 3-deazaadenosine and 5'-deoxy-5'-isobutylthio-3-deazaadenosine (3-deaza-SIBA)

3-Deazaadenosine and 5′-deoxy-5′-isobutylthio-3-deazaadenosine (3-deaza-SIBA) inhibits replication of both herpes simplex type 1 virus and the RNA type C virus, HL-23. Oncogenic transformation caused by SV40 and HL-23 are also blocked by either compound. Both compounds exhibit relatively low cytotoxicity at the anti-viral concentrations.     

Genetics of glucosephosphate isomerase in Aedes togoi (Diptera: Culicidae)

The genetics of glucosephosphate isomerase (E.C. 5.3.1.9) in two strains (Malaysian and Taiwan) of Aedes togoi is reported. Three electrophoretic phenotypes were present in both sexes. The zymogram patterns were identical in both strains of A. togoi. The phenotypes were governed by a pair of codominant alleles. The allele frequency of the slow-moving band was 0.63 in the Malaysian strain and was 0.86 and 0.82 in F161 and F169 generations, respectively, of the Taiwan strain. The sample studied was in good accord with Hardy-Weinberg expectations.     

Ectoprotein kinase activity of the isolated rat adipocyte.

Intact adipocytes exhibit ectoprotein kinase activity as reflected by their ability to catalyze the transfer of the terminal phosphate of (γ-³²P) ATP to histone added to a cell suspension. This activity is substrate, time and cell number dependent. Lineweaver-Burk plots gave Km and Vmax values for ATP of 5 × 10^?5 M and 7.14 pmoles/min/1.5 × 10⁵ cells. Cyclic AMP but not cyclic GMP in μM concentrations stimulates ectoprotein kinase activity. The controlled tryptic digestion of intact cells results in reduction of ectoprotein kinase activity. This activity is not due to leakage of intracellular protein kinases during the preparative procedure nor to penetration of histone into the cells. Additional phosphoproteins not accessible to endogenous protein kinase activity are also localized on the external surface of the intact fat cell.     

Guanidoacetate methyltransferase. Purification and molecular properties.

Guanidoacetate methyltransferase has been purified about 140-fold from pig liver. Polyacrylamide gel electrophoresis of the purified enzyme showed four protein bands, each of which is associated with guanidoacetate methyltransferase activity. During gel electrophoresis at pH 3 in 8 M urea, guanidoacetate methyltransferase migrated as a single component. The molecular weight of the purified guanidoacetate methyltransferase was estimated to be 31,000 by sodium dodecyl sulfate-gel electrophoresis, which also showed only one protein component with guanidoacetate methyltransferase activity. This molecular weight is in agreement with that estimated by Sephadex G-75 chromatography. Guanidoacetate methyltransferase is inhibited by adenosylhomocysteine, 3-deazaadenosylhomocysteine, and sinefungin with Ki values of 16 microM, 39 microM, and 18 microM, respectively.     

The action of the adenosylhomocysteine hydrolase inhibitor, 3-deazaadenosine,on phagocytic function of mouse macrophages and human monocytes

An inhibitor of adenosylhomocysteine hydrolase, 3-deazaadenosine, caused profound inhibition of phagocytosis of opsonized erythrocytes by mouse resident peritoneal macrophages $\text{in}\text{vitro}$. The inhibition was evident at concentrations as low as 2×10^?7M, and increased with increasing concentration and time of exposure to the analogue. It was not associated with detachment of the macrophage monolayers or with loss of cell viability. Although the inhibition was not reversible, progression of the functional impairment was interrupted by washing out the analogue. In striking contrast, phagocytic function of human blood monocytes was unaffected by 3-deazaadenosine.     

Oxidation-reduction potential measurements on chloroperoxidase and its complexes.

The oxidation-reduction potential of chloroperoxidase, an enzyme which catalyzes peroxidative chlorination, bromination, and iodination reactions, has been investigated. In addition to catalyzing biological halogenation reactions, chloroperoxidase is unusual in that the carbon monoxide complex of ferrous chloroperoxidase shows the typical long wavelength Soret absorption associated with P-450 hemoproteins. The pH dependence of the chloroperoxidase oxidation-reduction potential shows a discontinuity around pH 4.7. Similarly, measurements of the affinity of ferrous chloroperoxidase for carbon monoxide monitored both by spectroscopic and potentiometric titration exhibit a discontinuity in the pH 4.7 region. Oxidation-reduction potential measurements on chloroperoxidase in a CO atmosphere also show a discontinuous pH profile. These results suggest that ferrous chloroperoxidase undergoes reversible modification at low pH and that these changes are reflected in the oxidation-reduction potential. The oxidation-reduction potential of chloroperoxidase at pH 6.9 is - 140 mV, close to that measured for cytochrome P-450cam in the presence of substrate. The oxidation-reduction potential of chloroperoxidase at pH 2.7, the pH optimum for enzymatic chlorination, is +150 mV. The oxidation-reduction potentials of the halide complexes of chloroperoxidase (chloride, bromide, and iodide) are essentially identical with the potential measurements on the native enzyme. These observations suggest that, although halide anions bind to the enzyme, they probably do not bind as an axial ligand to the heme ferric iron.     

The interaction of collagen with the hydrophobic fluorescent probe-2-p-toluidinylnaphthalene-6-sulfonate.

Three kinds of fluorescence enhancement result from the interaction of 2-p-toluidinylnaphthalene-6-sulfonate and calf-skin collagen. They are negatively cooperative, independent, and highly cooperative fluorescence enhancement. In the independent region at pH 3.7, the binding number is about 36 moles of 2-p-toluidinylnaphthalene-6-sulfonate per mole of tropocollagen with a binding constant of 2.0 × 10⁴ M^?1; with ΔG = ?5.7 kcal/mole, ΔH = ?4.0 kcal/mole, and ΔS = 6 e.u. The pH dependence of fluorescence of native collagen shows that the deprotonated forms of the β and γ carboxyl groups of aspartic and glutamic acid decrease the intensity, possibly by charge repulsion of the negatively charged sulfonate group of 2-p-toluidinylnaphthalene-6-sulfonate. The positive charge of lysine is found to be unimportant in the interaction of 2-p-toluidinylnaphthalene-6-sulfonate with collagen. Fluorescence enhancement is caused mainly by the hydrophobic interactions of 2-p-toluidinylnaphthalene-6-sulfonate and collagen. Salt bridge formation between basic and acidic side chains in very low salt concentration may be detectable by 2-p-toluidinylnaphthalene-6-sulfonate fluorescence.     

A trypsin-resistant heme peptide from cardiac cytochrome c1.

A tryptic resistant heme peptide has been prepared and purified from cardiac cytochrome c1. This purified peptide is not further hydrolyzed by reactions of other proteolytic enzymes, such as pronase. The peptide contains 2 residues each of serine, cysteine and valine, and 1 residue each of alanine, methionine, tyrosine, histidine, arginine, proline, glutamic acid (glutamine) and aspartic acid. The intensity of the absorption spectrum of the peptide has been found to be dependent upon, but the positions of the absorption maxima do not vary with, concentration. The heme peptide does not show multiple splitting of absorption peaks at liquid N2 temperatures as does the intact cytochrome C1. However, cyanide rapidly reacts with the peptide and causes significant spectral changes. CD spectra of the peptide exhibit a typical profile of a non-structured heme peptide with positive CD bands in the Soret region and around 250 nm, and a broad negative extreme of 320-360 nm. The similarities and differences between the tryptic resistant heme peptides from cytochromes c1 and c have been compared.