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Biomedical subjects

T Ikenaka

Publications and source records attributed to T Ikenaka.

At least 127 records · Page 7Linked to original sources
PubMed1979

alpha-Fetoprotein as a carrier protein in plasma and its bilirubin-binding ability.

The bilirubin-binding ability of human alpha-fetoproteins, which were purified from fetal cord serum and from ascites fluid of a hepatoma-bearing patient, was examined by the difference spectrum and the Jacobsen peroxidase methods. The difference spectrum observed as a result of the specific binding of bilirubin to alpha-fetoprotein had a maximum at 482 nm, and this pattern was quite similar to that observed for serum albumin. The result obtained by the difference spectrum method showed that 1 mol of each alpha-fetoprotein bound 1 mol of bilirubin at pH 8.3 and that the dissociation constants of the complexes of bilirubin with fetal alpha-fetoprotein and hepatoma-derived alpha-fetoprotein were 2.6 x 10(-7) and 5.0 x 10(-7) M, respectively. The Jacobsen enzymatic method using horseradish peroxidase gave the same values for molar binding ratios and similar dissociation constants, 7.1 x 10(-7) M for fetal alpha-fetoprotein and 7.4 x 10(-7) M for hepatoma-derived alpha-fetoprotein. These results indicate that alpha-fetoprotein may function as a carrier protein for bilirubin as has been shown for serum albumin.

Bilirubin↗
PubMed1978

Studies on soybean trypsin inhibitors, XII. Linear sequences of two soybean double-headed trypsin inhibitors, D-II and E-I.

Soybean inhibitor D-II is an inhibitor of bovine trypsin. Sequence analysis was carried out on the reduced and S-carboxymethylated protein by conventional methods to establish the complete amino acid sequence. The sequence of D-II indicated high homology with other legume inhibitors, but it was unique because of the occurrence of identical residues (arginine) at both of the reactive sites. This structure is thought to reflect that of a prototype double-headed inhibitor. The possible evolutionary process of the legume double-headed inhibitors is discussed on this basis. Comparison with another soybean inhibitor C-II suggested that a single methionine (C-II)-glutamine (D-II) replacement at the P2'position resulted in the loss of alpha-chymotrypsin inhibitory activity of D-II. The results of a hydrogen peroxide oxidation experiment on C-II supported this suggestion. The sequence of the amino-terminal 21 residues of inhibitor E-I was determined using a sequentor. It was shown that this inhibitor lacks the amino-terminal nine residues of D-II.

Amino Acid Sequence↗
PubMed1978

Studies on soybean trypsin inhibitors. XIII. Preparation and characterization of active fragments from Bowman-Birk proteinase inhibitor.

Soybean Bowman-Birk inhibitor, a double-headed inhibitor of trypsin and alpha-chymotrypsin, was treated with cyanogen bromide and then pepsin to yield two inhibitory active fragments. Structural investigation showed that one of the fragments was derived from the trypsin inhibitory domain and the other from the chymotrypsin inhibitory domain of the inhibitor. In contrast to the unusual stability of the native inhibitor, the separated domains were less stable and could be inactivated with excess proteinases. These results suggest that the legume double-headed inhibitors acquired their unusual stability by duplicating an ancestral single-headed structure.

Amino Acid Sequence↗
PubMed1978

Fluorometric measurement of urinary alpha-L-iduronidase activity.

A fluorogenic substrate for alpha-L-iduronidase, 4-methylumbelliferyl alpha-L-iduronide, has been newly synthesized and the enzyme activity has been measured in urine samples obtained from normal persons and patients suffering from mucopolysaccharidosis. Urine samples derived from a patient with Scheie syndrome showed greatly reduced activity compared with a normal adult at a similar age. This patient exhibited a high level of urinary excretion of dermatan sulfate and heparan sulfate, which could be interpreted in terms of her low alpha-L-iduronidase activity. The use of the fluorogenic substrate has some advantages over existing methods because of the high sensitivity and the relative ease of handling, and it should be useful not only for diagnosis but also for following the purification process of the enzyme.

Adult↗
PubMed1978

Identification of beta-aspartylglycine in uremic serum and its toxicity.

An unidentified ninhydrin-positive substance of acidic nature was found in the serum of uremic patients. This substance was isolated from hemodialysate by the methods of ion-exchange chromatography, gel-filtration and paper electrophoresis, and identified as beta-aspartylglycine by amino acid analysis, N-terminal amino acid determination and comparison with authentic sample synthesized in this laboratory. The quantitative determination of beta-aspartylglycine in serum revealed that the serum concentrations of beta-aspartyl-glycine in uremic patients increased much higher than those in normal subjects. The toxicity of beta-aspartylglycine in mice with acute renal failure induced by uranyl acetate was investigated. The mice given more than 1,0 g/kg body weight of beta-aspartylglycine showed behavioral alterations: low response to the stimuli and low activity, and some mice died by the injection of 4.0 g/kg body weight of the peptide. These results suggested that beta-aspartyl-glycine might be a possible factor which influences the development of uremic toxaemia.

Acute Kidney Injury↗
PubMed1978

Copper(II)-binding ability of human alpha-fetoprotein.

The copper(II)-binding ability of human alpha-fetoproteins, which were purified from umbilical cord serum and from ascites fluid of a hepatoma-bearing patient, was examined by equilibrium dialysis and gel filtration methods. The pH dependence of the copper(II)-binding ability of alpha-fetoprotein was quite similar to that of albumin. Alpha-fetoprotein bound 1 mol of copper(II) ion per mol of protein above pH 6.0 and 0.5 mol of copper(II) ion at pH 5.4, which is close to the pK value of the imidazole group of histidine. Photooxidation of alpha-fetoprotein in the presence of methylene blue resulted in the loss of the copper(II)-binding ability of the protein in parallel with the destruction of the histidyl residues. A synthetic amino-terminal undecapeptide of alpha-fetoprotein also bound copper(II) ion. These results indicate that the histidyl residue at the amino-terminal region of alpha-fetoprotein plays an important role in the copper(II)-binding ability of the protein.

Carcinoma, Hepatocellular↗
PubMed1977

Collagen glycopeptides from the sea cucumber Stichopus japonicus.

Structures of several hydroxylysine-containing glycopeptides derived from the body wall of the sea cucumber have been determined. The glycosylated hydroxylysines were all the Y positions of Gly-X-Y triplets. They are thought to be distributed throughout the peptide chain, in contrast to vertebrate skin collagens. One glycopeptide demonstrated the existence of the sequence Gly-Gly-Hyp in invertebrates for the first time.

Amino Acid Sequence↗
PubMed1977

Studies on soybean trypsin inhibitors. X. Isolation and partial characterization of four soybean double-headed proteinase inhibitors.

Four Bowman-Birk type double-headed inhibitors (B, C-II, D-II, and E-I) were isolated from soybeans. Inhibitor B was different from Bowman-Birk inhibitor only in chromatographic behavior. One mole of C-II inhibited one mole each of bovine trypsin and bovine alpha-chymotrypsin, probably at the same site, and porcine elastase at another reactive site. In the ordinary assay system D-II and E-I inhibited only trypsin activity at a non-stoichiometric inhibitor-enzyme ratio of 1:1.4, and the complexes had rather high dissociation constants. These inhibitors were all inactive toward subtilisin BPN'.

Amino Acids↗
PubMed1977

Studies on soybean trypsin inhibitors. XI. Complete amino acid sequence of a soybean trypsin-chymotrypsin-elastase inhibitor, C-II.

Soybean inhibitor C-II, which inhibits trypsin, alpha-chymotrypsin, and elastase, was reduced and S-carboxymethylated, and digested with trypsin. The amino acid sequences of the resulting tryptic peptides were determined by conventional methods, establishing the complete 76-amino acid sequence of the inhibitor. Inhibitor C-II was found to be homologous with soybean (Glycine max) Bowman-Birk inhibitor and more closely related to an inhibitor from garden beans (Phaseolus vulgaris). The homology with these inhibitors and the limited proteolysis of C-II indicated the reactive sites of C-II for elastase and trypsin to be alanine-22 and arginine-49, respectively. Arginine-49 was also identified as a reactive site for alpha-chymotrypsin. It was found that only a few replacements of one or two amino acid residues around the reactive sites resulted in considerable alteration of the inhibitory specificity.

Amino Acid Sequence↗
PubMed1977

Elevation of serum levels of beta-aminoisobutyric acid in uremic patients and the toxicity of the amino acid.

A reliable method for the determination of beta-aminoisobutyric acid in serum was developed utilizing an automated amino acid analyzer. The serum concentrations of beta-aminoisobutyric acid were determined in 20 normal subjects and in 71 uremic patients. The mean serum level of beta-aminoisobutyric acid was markedly increased in the uremic patients to 0.856 +/- 0.910 (mean +/- SD) mg/100 ml as compared with a normal value of 0.026 +/- 0.027 mg/100 ml. The distribution of serum beta-aminoisobutyric acid level in uremic patients was wide-spread, and there was no correlation between the serum levels of the amino acid and those of urea nitrogen, creatinine and uric acid. The toxicity of beta-aminoisobutyric acid on mice with acute renal failure induced by uranyl acetate was investigated and compared with that of alpha-amino-n-butyric acid and gamma-amino-n-butyric acid. All mice given more than 4 g/kg body wt of beta-aminoisobutyric acid showed twitching and cramps, and some of them died. However, the control mice given an equivalent dose of alpha-amino-n-butyric acid or gamma-amino-n-butyric acid showed no change. These results suggest that beta-aminoisobutyric acid might be a factor influencing the development and progression of uremic toxemia.

Acute Kidney Injury↗
PubMed1977

Comparative chemical structures of human alpha-fetoproteins from fetal serum and from ascites fluid of a patient with hepatoma.

Human alpha-fetoproteins were purified from umbilical cord serum and from ascites fluid of a patient with hepatoma by affinity chromatography, and their chemical compositions and terminal sequences were compared. The amino acid compositions of these alpha-fetoproteins were similar and in good agreement with the values reported by other investigators. The COOH-terminal 5-amino acid sequence determined by carboxypeptidase digestion and the NH2-terminal 20-amino acid sequence determined by an automated sequence analyzer revealed that both alpha-fetoproteins had the same terminal sequences of amino acids. The sequence analysis showed that a part of each of the proteins lacked its NH2-terminal residues for one or three amino acids. A small difference in the carbohydrate composition of each alpha-fetoprotein was observed. It was concluded that alpha-fetoproteins from fetal serum and from ascites fluid of a patient with hepatoma had very similar structures.

Amino Acid Sequence↗
PubMed1976

Identification of beta-aminoisobutyric acid in uremic serum.

An unidentified ninhydrin-positive substance found in uremic sera but not found in normal sera was isolated by gel-filtration through Sephadex G-75 followed by high voltage paper electrophoresis (pH 3.5), and identified as beta-aminoisobutyric acid using paper chromatography and automated amino acid analyzer. The quantitative determination of beta-aminoisobutyric acid in serum revealed that the level of beta-aminoisobutyric acid in uremic sera was much higher than that of normal sera. Gas chromatographic determination of the enantiomorphs of beta-aminoisobutyric acid showed that uremic sera contain R- and S-isomers of the amino acid, but with the R-isomer as the dominating form.

Aminoisobutyric Acids↗