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T Ikenaka

Publications and source records attributed to T Ikenaka.

At least 73 records · Page 4Linked to original sources
PubMed1987

The structure of Bowman-Birk type protease inhibitor A-II from peanut (Arachis hypogaea) at 3.3 A resolution.

The structure of Bowman-Birk type protease inhibitor (A-II from peanut) is described at 3.3 A resolution. The molecules form a tetramer with 222 local symmetry in our crystals. Each monomer has an elongated shape with approximate dimensions of 45 X 15 X 15 A and consists of two distinct domains. The three-dimensional structures of the two domains are similar and are related by the intramolecular approximate twofold rotation axis. The two independent protease binding sites protrude from the molecular body on opposite sides. A scheme for the molecular evolution of the double-headed Bowman-Birk type protease inhibitors is proposed, based on the three-dimensional structure.

Arachis↗
PubMed1986

1H-NMR analysis of the sugar structures of glycoproteins as their pyridylamino derivatives.

The 1H-NMR spectra of a series of pyridylamino (PA-) derivatives of oligosaccharides were obtained and compared with those of the corresponding asparagine-linked sugar chains in order to elucidate the effect of the PA-group on the chemical shifts of structural-reporter signals. The effects were found to be localized within the two residues from the end group. Thus, the data for asparagine-linked chains in the literature are applicable to PA-derivatives, so the combination of pyridylamination and NMR measurements greatly reduces the time required for structure analysis of sugar chains of glycoproteins, because the isolation and purification of the chains as PA-derivatives are easy and efficient.

Asparagine↗
PubMed1986

Conformational studies by 1H nuclear magnetic resonance of the trypsin-chymotrypsin inhibitor B-III from peanuts and its enzymatically modified derivative.

The conformation of the peanut inhibitor B-III was investigated by 1H NMR at 500 MHz. Resonances for about 30% of the residues were assigned and/or identified by conventional and two-dimensional 1H NMR measurements. The conformation of the modified inhibitor B-IIIRS, obtained by the cleavage of the peptide bonds of B-III at the first reactive site, Arg(10)-Arg(11), and second reactive site, Arg-(37)-Ser(38), was also investigated. Edman degradation was used to identify resonances of the residues adjoining the scissile sites. A comparison of the behavior of the resonances corresponding to Ala(12), Tyr(15), Phe(16), and Thr(37) in B-III and B-IIIRS indicated that the only conformational differences between the two proteins were those from the S-S loops containing the two reactive sites. From the similar behavior of Leu(7), Phe(24), His(26), Ala(29), five valine, and four threonine resonances in both proteins, it is suggested that the S-S loops that do not contain a scissile bond (the core region of the inhibitor) were rigid. Thus, no conformational change of the core region was observed upon cleavage of the reactive sites.

Amino Acid Sequence↗
PubMed1986

Measurement of cyclomaltodextrin glucanotransferase activity by high-performance liquid chromatography using a fluorogenic substrate.

A mixture of p-nitrophenyl O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D- glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D- glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D- glucopyranoside (FG5P) and p-nitrophenyl alpha-D-glucoside (GP) was incubated with cyclomaltodextrin glucanotransferase (CGTase) [EC 2.4.1.19]. Analysis of the digest by HPLC showed that the products were p-nitrophenyl O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D- glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D- glucopyranosyl-(1----4)-alpha-D-glucopyranoside (FG4P) and p-nitrophenyl alpha-D-maltoside (G2P), and no other product could be detected. Based on the reaction, a sensitive method to assay for CGTase was developed.

Bacillus↗
PubMed1986

Structure of a sugar chain of a protease inhibitor isolated from barbados pride (Caesalpinia pulcherrima Sw.) seeds.

An asparagine-linked sugar chain of a protease inhibitor from barbados pride (Caesalpinia pulcherrima Sw.) was liberated by hydrazinolysis. After N-acetylation, the reducing end residue of this carbohydrate unit was coupled with 2-aminopyridine and the pyridylamino (PA-) derivative was purified by gel-filtration and reversed-phase HPLC. The structure of the resulting PA-sugar chain was determined mainly by stepwise exoglycosidase digestions and 500 MHz 1H-NMR spectroscopy and proved to be as follows: (formula; see text).

Carbohydrate Conformation↗
PubMed1986

Crystallization of Bowman-Birk type protease inhibitor (peanut) and its complex with trypsin.

Crystallization and preliminary crystallographic study of Bowman-Birk type protease inhibitors, A-I, A-II, and B-III from peanut seeds (Arachis hypogaea), and of the A-II + trypsin complex were carried out. A-II, with 70 amino acid residues, crystallizes in a trigonal system, P3(1)21 (or P3(2)21), a = 71.8, c = 65.9 A, Z = 12 or 18. The A-I crystal is isomorphous with that of A-II, indicating that the N-terminal residues are in a disordered state in both crystals. The B-III crystal is monoclinic, C2, a = 119.6, b = 69.6, c = 94.2 A, beta = 115.1 degrees, Z is about 40. The A-II + trypsin complex crystallizes in an orthorhombic system, P2(1)2(1)2(1), a = 55.5, b = 56.0, c = 182.1 A, Z = 4.

Arachis↗
PubMed1986

Studies on the methods for the determination of phosphorylation sites in highly phosphorylated peptides or proteins: phosphorylation sites of hen egg white riboflavin binding protein.

To determine the phosphate binding sites in hen egg white riboflavin binding protein (RBP), a highly phosphorylated peptide, which consisted of 23 amino acid residues including eight phosphoserines, was isolated from the tryptic digest of reduced and carboxymethylated RBP. The conditions of the beta-elimination-addition reaction to convert phosphoserine residues in the peptide to cysteic acids, S-methylcysteines, alanines, and beta-methylaminoalanines (DL-alpha-amino-beta-methylamino propionic acid) were examined. These converted peptides were purified by HPLC and subjected to Edman degradation. The results of Edman degradation indicated that the S-methylcysteine derivative of the peptide gave the most satisfactory result for determining the phosphate binding sites in the peptide. The phosphorylation sites of the peptide determined by the method mentioned above are as follows: His182-Leu-Leu-Ser185-Glu-Ser(P)-Ser(P)-Glu-Glu190-Ser (P)-Ser(P)-Ser(P)-Met-Ser195(P)-Ser(P)-Ser(P)-Glu-Glu-. These studies indicated that the conversion of phosphoserines in phosphoproteins to S-methylcysteines followed by Edman analysis was a useful method for the elucidation of the phosphorylation sites in phosphopeptides.

Amino Acid Sequence↗
PubMed1986

Differential rate assay of human pancreatic and salivary alpha-amylases in serum using two coupled enzymes.

p-Nitrophenyl O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D-glucopyranosyl-(1----4)-O-alpha- D-glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D- glucopyranosyl-(1----4)-alpha-D-glucopyranoside (FG5P) is hydrolyzed by human pancreatic a-amylase (HPA) or salivary alpha-amylase (HSA) to O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D- glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-D-glucose (FG3) and p-nitrophenyl alpha-maltoside or to O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D-glucopyranosyl-(1----4)-O-alpha- D-glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-D-glucose (FG4) and p-nitrophenyl alpha-glucoside. The use of alpha-D-glucosidase (maltase) [EC 3.2.1.20] of Saccharomyces carlsbergensis and oligo-1,6-glucosidase (isomaltase) [EC 3.2.1.10] of bakers' yeast as coupled enzymes differentiates between the two reactions, because alpha-D-glucosidase liberates p-nitrophenol from both p-nitrophenyl alpha-glucoside and p-nitrophenyl alpha-maltoside, but oligo-1,6-glucosidase liberates it only from p-nitrophenyl alpha-glucoside. HPA produces more FG4 and p-nitrophenyl alpha-glucoside than HSA. Taking advantage of the differences in the action of the two amylases and in the substrate specificity of the coupled enzymes, we have developed a new colorimetric differential rate assay of alpha-amylases in human serum.

Glucosides↗
PubMed1986

Fluorometric rate assay of alpha-amylase using an intramolecularly-quenched fluorescent substrate (FG5P).

The complete hydrolysis of a fluorogenic derivative of rho-nitrophenyl alpha-maltopentaoside, FG5P, by human salivary alpha-amylase, resulted in a 5-fold increase in fluorescence. This is due to disruption of the intramolecular quenching of the fluorescence of the 2-pyridylamino residue by the rho-nitrophenyl residue by separation of the two residues. This change of fluorescence accompanying the cleavage of the glucosidic bond was exploited to develop a fluorometric rate assay of alpha-amylase in human serum.

Chromatography, High Pressure Liquid↗
PubMed1986

Purification and characterization of proteinase inhibitors from winged bean (Psophocarpus tetragonolobus (L.) DC.) seeds.

Seven proteinase inhibitors were isolated from winged bean seeds by ion-exchange chromatographies. These inhibitors had molecular weights of around 20,000, included four half-cystine residues, and were Kunitz-type inhibitors. Two (WTI-2 and 3) inhibited bovine trypsin strongly and four (WCI-1, 2, 3, and 4) inhibited bovine alpha-chymotrypsin, but in different ways. One mole of WCI-2 or -3 could inhibit 2 mol of alpha-chymotrypsin. The remaining inhibitor (WTCI-1) could bind both bovine trypsin and alpha-chymotrypsin at the molar ratio of 1:1, but not simultaneously. All four chymotrypsin inhibitors cross-reacted with rabbit anti-WCI-3 serum, while the other inhibitors did not.

Amino Acids↗
PubMed1986

Inspection of active sites of human salivary alpha-amylase isozymes by means of non-reducing-end substituted maltooligosaccharides with 2-pyridylamino residue.

The modes of action of four alpha-amylase isozymes, which were purified from human saliva, on p-nitrophenyl alpha-maltopentaoside (G5P), maltohexaitol (G6R), and their 2-pyridylamino derivatives, p-nitrophenyl O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D-glucopyranosyl-(1----4)-O-alpha- D-glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D- glucopyranosyl-(1----4)-alpha-D-glucopyranoside (FG5P) and O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D-glucopyranosyl-(1----4)- O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-O- alpha-D-glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-D- glucitol (FG6R) were examined at various pH values. No differences in their modes of action on the substrates was found. Irrespective of which enzyme was used, the molar ratio of the hydrolysis products of G5P or G6R was almost constant at any pH examined. On the other hand, those of FG5P and FG6R varied with pH such that predominantly O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D-glucopyranosyl- (1----4)-O-alpha-D-glucopyranosyl-(1----4)-D-glucose (FG3) was formed at high pH ranges, while the formation of O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D-glucopyranosyl-(1----4)- O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-D-gl ucose (FG4) increased at lower pH. The result indicates that the binding mode of FG5P or FG6R to the active sites of the enzymes changed with pH; namely, interactions between the 2-pyridylamino residue of the substrates and some amino acid residue(s) located in the active sites were influenced by pH.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗
PubMed1986

The structure of sugar chains of Japanese quail ovomucoid. The occurrence of oligosaccharides not expected from the classical biosynthetic pathway for N-glycans; a method for the assessment of the structure of glycans present in picomolar amounts.

While the structure of the major oligosaccharide of Japanese quail ovomucoid was reported earlier (Hase, S. et al. (1982) J. Biochem. 91, 735-737), the structures of the minor oligosaccharide units were investigated for the first time in the present studies. For this purpose, the glycans of the protein were liberated from the polypeptide chain by hydrazinolysis. After N-acetylation, the reducing ends of the oligosaccharides obtained were coupled with 2-aminopyridine, and then the resulting fluorescent derivatives were purified by Bio-Gel P-2 column chromatography and reversed-phase HPLC. The chemical structures of two minor oligosaccharide units were determined with the aid of exoglycosidases, and by methylation analysis and Smith degradation. The results demonstrated that the ovomucoid contains the following two monoantennary glycans: Man alpha 1-6(Gal beta 1-4GlcNAc beta 1-2Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4GlcNAc and Gal beta 1-4GlcNAc beta 1-2Man alpha 1-6(Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4GlcNAc. The latter structure was not predicted by the classical metabolic pathway for the N-glycans to be formed. The structures of three additional minor heterosaccharides were deduced from their elution positions on HPLC together with the results of determination of their molecular sizes and the HPLC elution positions of their enzymatic degradation products. It is noteworthy that for the latter procedure for the estimation of the structures of oligosaccharides only minute quantities of glycans (several hundreds pmol) are required.

Amino Acids↗
PubMed1985

Microquantitative analysis of neutral and amino sugars as fluorescent pyridylamino derivatives by high-performance liquid chromatography.

A method for the quantitation of picomole amounts of neutral and amino sugars in glycoconjugates was developed. Glycoconjugates were hydrolyzed with a mixture of equal amounts of 4 M trifluoroacetic acid and 4 M hydrochloric acid, and the free amino groups were acetylated. Sugars were coupled with 2-aminopyridine. After the excess reagents were removed by gel-permeation high-performance liquid chromatography, the fluorescent pyridylamino derivatives of sugars were separated and quantified by high-performance liquid chromatography on a reversed-phase column. This method allowed the determination of 0.01-10 nmol of sugars. About 100 pmol of several glycoconjugates were analyzed by the present method, with satisfactory results.

Amino Sugars↗
PubMed1985

Amino acid sequence of Streptomyces metallo-proteinase inhibitor from Streptomyces nigrescens TK-23.

Streptomyces Metallo-Proteinase Inhibitor (S-MPI) consists of 102 amino acid residues, including one methionine and two disulfide bridges. The complete amino acid sequence of S-MPI, including two disulfide bridges, was determined by sequencing of tryptic and chymotryptic peptides of two fragments obtained by cyanogen bromide cleavage followed by reduction and S-pyridylethylation of the protein. Incubation of the inhibitor with thermolysin slowly cleaved one peptide bond, Cys(64)-Val(65), which might be a reactive site of S-MPI.

Amino Acid Sequence↗
PubMed1985

Comparison of the amino acid sequences of hen plasma-, yolk-, and white-riboflavin binding proteins.

The amino acid sequence of hen egg yolk-riboflavin binding protein (yolk-RBP) was determined by conventional methods. The sequence was identical with that of hen egg white-riboflavin binding protein except that their carboxyltermini were different, that of yolk-RBP lacked 11 or 13 amino acid residues, while hen plasma-RBP had the same C-terminal sequence as white-RBP. This indicated that the C-terminal 11 or 13 amino acid residues in plasma-RBP might be cleaved off during the incorporation from the blood into the oocyte or in the yolk fluid. Yolk-RBP had the same characteristics as white-RBP, such as N-terminal pyroglutamic acid, polymorphism in the amino acid sequence (Lys/Asn) at the fourteenth residue from the N-terminal end, carbohydrate chains attached to both Asn(36) and Asn(147) residues, and phosphate groups bound to some serine residues in the sequence of Ser(185) to Ser(197) as a cluster. These results led us to the conclusion that yolk- and white-RBPs are bio-synthesized from the same gene in the different organs (liver and oviduct). The carbohydrate composition of yolk-RBP was identical to that of plasma-RBP but different from that of white-RBP showing that the processing of the carbohydrate chains in the liver was different from that in the oviduct.

Amino Acid Sequence↗
PubMed1985

Amino acid sequence of protein alpha-amylase inhibitor from Streptomyces griseosporeus YM-25.

The amino acid sequence of a protein alpha-amylase inhibitor from Streptomyces griseosporeus YM-25 (Haim II), which consists of 77 amino acid residues, including two disulfide bridges, was determined by conventional methods. One of the disulfide bridges was found to be located between Cys(6) and Cys(22), and the other between Cys(40) and Cys(67) from the results of structure analyses of the two cystine-containing peptides obtained from the thermolysin digest of the native inhibitor.

Amino Acid Sequence↗
PubMed1985

Preparation of non-reducing-end substituted p-nitrophenyl alpha-maltopentaoside (FG5P) as a substrate for a coupled enzymatic assay for alpha-amylases.

p-Nitrophenyl O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D-glucopyranosyl-(1----4)-O-alpha-D - glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D- glucopyranosyl-(1----4)-alpha-D-glucopyranoside, FG5P, was prepared, taking advantage of the action of Bacillus macerans cyclodextrin glucanotransferase on a mixture of O-6-deoxy-6-[(2-pyridyl)-amino]-alpha-D-glucopyranosyl-(1----4)-O-alpha- D- glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-O-alpha-D- glucopyranosyl-(1----4)-O-alpha-D-glucopyranosyl-(1----4)-D-glucose and p-nitrophenyl alpha-glucoside. The maltopentaose derivative is resistant to alpha-glucosidase and is suitable as a substrate for the alpha-amylase assay coupled with alpha-glucosidase in which the activity of alpha-amylase is determined by measuring the amount of p-nitrophenol liberated by alpha-glucosidase from p-nitrophenyl alpha-glucoside and p-nitrophenyl alpha-maltoside produced by the action of alpha-amylase. This alpha-amylase assay method was applied for determination of alpha-amylases in human serum.

Bacillus↗