Kiyoshi Abe

Relevance of the arginine transport activity to the nitric oxide synthesis in mouse peritoneal macrophages stimulated with bacterial lipopolysaccharide

Transport of arginine and production of nitrite have been investigated in mouse peritoneal macrophages stimulated with bacterial lipopolysaccharide (LPS). The arginine transport activity was induced by LPS at very low concentration (maximally induced at 1 ng/ml), whereas much higher concentration of LPS was required for the induction of nitrite production. Arginine was more concentrated in the cells when its transport activity was induced. Lysine, which is a competitive inhibitor of the transport of arginine, neutralized the concentrative effect of the induced transport activity and thus inhibited the nitrite production. Induction of the arginine transport activity seems to be prerequisite to the enhanced synthesis of nitric oxide in activated macrophages.

Differences in C-terminal amino acid sequences between erythrocyte and liver cytochrome b5 isolated from pig and human: Evidence for two tissue-specific forms of cytochrome b5

Two forms of cytochrome b 5, a soluble erythrocyte form and a membrane‐bound liver form, were purified from pig and human, and structural differences between them were analyzed. Porcine and human erythrocyte cytochrome b 5 consisted of 97 amino acid residues and contained the same catalytic domain structure (residue 1–96) as that of the corresponding liver cytochrome b 5, but had one amino acid replacement at the C‐terminus (residue 97). These results suggest that erythrocyte cytochrome b 5 is not derived from the liver protein by proteolysis but a translational product from another distinct mRNA of cytochrome b 5.Two forms of cytochrome b5, a soluble erythrocyte form and a membrane-bound liver form, were purified from pig and human, and structural differences between them were analyzed. Porcine and human erythrocyte cytochrome b5 consisted of 97 amino acid residues and contained the same catalytic domain structure (residues 1-96) as that of the corresponding liver cytochrome b5, but had one amino acid replacement at the C-terminus (residue 97). These results suggest that erythrocyte cytochrome b5 is not derived from the liver protein by proteolysis but a translational product from another distinct mRNA of cytochrome b5.

Spectral and carbon monoxide binding properties of Fe(II) picket-fence porphyrin and protoheme bound to liposomes.

Abstract Spectral and CO binding properties of liposome bound heme compounds, Fe(II) picket-fence porphyrin and protoheme, were examined. Phosphatidylethanolamine and phosphatidylcholine were used to make liposomes. Liposome-bound protoheme showed a very low CO affinity, whereas liposome-bound Fe(II) picket-fence porphyrin showed a high affinity. Addition of the ligand, 1-methylimidazole, modulated the CO affinities of both types of complexes to a level comparable to that of hemoglobin. However, autoxidation rates of the liposome bound heme compounds were still considerably high, and no stable oxygenated form could be observed.