Possible role of transferrin in exfoliation syndrome.

Protein concentration was measured in 30 exfoliation syndrome samples and 22 age matched controls. Exfoliation samples contained significantly more protein than controls. We also analyzed by SDS gel electrophoresis 32 aqueous samples, 12 with exfoliation syndrome and 20 age matched controls. A novel finding in all samples was a double band with 77 kDa and 78 kDa. These bands probably represent transferrin isoforms, with different carbohydrate side chains. Exfoliation samples contained a lower amount of the 77 kDa band in comparison to the amount of the 78 kDa band. The lower relative concentration of this transferrin isoform in the exfoliation syndrome samples may be indicative of its possible involvement in the disorder. A different oligosaccharide side chain in combination with a relatively high protein concentration may lead to sedimentation of this molecule. On the other hand, laminin, a glycoprotein detected previously in exfoliation material, contains similar oligosaccharide side chains with transferrin. Thus the oligosaccharide side chains of both proteins may be influenced by the same factors.

Increased frequency of the rare PstI allele (P2) in a population of CAD patients in northern Greece.

Restriction fragment length polymorphisms (RFLPs) at the apolipoprotein AI-CIII-AIV gene cluster and their association with coronary artery disease (CAD) and lipid levels were studied in a Northern Greek population. Ninety-five patients with CAD and fifty-four normal controls, angiographically proven, were included in this study. Using genomic hybridization techniques, three polymorphic restriction sites were identified at this locus: the PstI at the 3' end of the apoAI gene, the SacI at the 3' non-coding region of the apoCIII gene and the PvuII at the intergenic region between the apoCIII-AIV genes. The rare allele (P2) arising from the absence of the PstI restriction site was observed with a significantly higher frequency (p < 0.01) in patients compared to normals (0.11 vs 0.02). In contrast, the rare allele for the SacI polymorphic site had a similar distribution among patients and controls (0.12 vs 0.16). The same was observed for the PvuII RFLP (0.04 vs 0.05). Correlation of lipid and apolipoprotein AI levels with the three RFLPs revealed no significant association, although apo AI and HDL were lower in patients with the P2 allele. Thus, in this Greek population, only the PstI polymorphism, among the polymorphic restriction sites examined, appears to be associated with CAD.

Cellular and tissue distribution of a single-strand-specific nuclease.

1. Specific antibodies which were raised against a single-strand-specific nuclease isolated from rat liver microsomes were used for characterizing this enzyme and determining its cellular and tissue distribution. 2. The single-strand-specific nuclease does not show any homology with other known nucleolytic enzymes. 3. It is mainly localized in microsomes and cytosol; traces of it are also found in nuclei, but it could not be detected in mitochondria. 4. Using the same specific antibodies we attempted to detect this nuclease in some other tissues which exhibit high metabolic rates, namely kidneys, heart and spleen. 5. Thus, with the aid of immunological techniques we were able to determine that at least part of the total poly(U) nucleolytic activity observed in kidney and heart is due to a nuclease immunologically identical to the enzyme under study. Kidneys were the best source for this enzyme.

Single-strand-specific nuclease from rat liver endoplasmic reticulum: characterization and mode of action.

1. The characteristics and mode of action of a single-strand-specific nuclease isolated from rat liver endoplasmic reticulum are investigated with respect to its DNA and RNA substrates. 2. The RNase activity of the enzyme is slightly influenced by the presence of divalent cations but the DNase activity is enhanced by divalent cations particularly Mn2+. 3. Activity is partially inhibited by the presence of EGTA; this effect is reversed most efficiently by the addition of Mn2+. 4. The enzyme exhibits small pH dependence between pH 6-9 and maximum activity is observed at pH 7-7.5 for both DNase and RNase activities. 5. Sulfhydryl group reagents do not affect its action but histidyl group reagents exert a small but definite effect. 6. The enzyme degrades DNA and RNA endonucleolytically producing fragments which possess 3'-OH and 5'-phosphate termini. 7. Monomers are not produced even after prolonged degradation. 8. The end product of poly(U)degradation ranges between two and four building blocks but the DNA product is longer probably due to considerable percentage of secondary structure.

Isolation and partial characterization of anglefish proglucagon.

Evidence is presented that proglucagon from anglefish islets is a single chain polypeptide with 78 amino acid residues and that the glucagon portion of it is liberated after tryptic cleavage. The most striking characteristic in the conversion of the anglerfish proglucagon to glucagon is that the cleaved peptide bonds display enormous sensitivity toward trypsin. Thus, conversion of the prohormone to glucagon occurs very rapidly within 3-10 min with a 1:500-1:1000 molar ratio of enzyme to substrate. Further, trypic cleavage of the anglerfish glucagon requires higher concentrations of trypsin (molar ratio 1:25 enzyme to substrate) and longer incubation time. The behavior of proglucagon and glucagon toward trypsin shows striking similarities with the tryptic conversion of anglerfish proinsulin to insulin.

The biosynthesis of ferredoxin in a cell-free system.

The investigation reported in this communication was concerned with the biosynthesis of ferredoxin in a cell-free system. A cell-free system, with the ability to incorporate amino acids into peptides and proteins, was developed from Cl. pasteurianum, and its requirements were established. After the incorporation of L-alanine-C(14), ferredoxin-C(14) was isolated in crystalline form with the aid of added carrier ferredoxin. Amino acid analyses and absorption spectra strongly indicated that the isolated ferredoxin-C(14), crystallized three times, was essentially free from impurities. Furthermore, experiments with Fe(59) strongly indicated that the iron may combine with the apoprotein after the latter is completely synthesized and released from the polysomes.