[A case of Hashimoto's thyroiditis occured during the course of sarcoidosis (author's transl)].
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
Y Nakae
Publications and source records attributed to Y Nakae.
Interactions of alpha- and beta-N-acetyl-D-glucosamines with hen and turkey lysozymes.
The binding constants of alpha- and beta-GlcNAc to hen and turkey lysozymes [EC 3.2.1.17] were determined at various pH's using the method proposed by Ikeda and Hamaguchi (1975) J. Biochem. 77, 1-16). The pH dependence of the binding of beta-GlcNAc to hen lysozyme was essentially the same as that for turkey lysozyme. The pH dependence curves of the binding constants of beta-GlcNAc to hen and turkey lysozymes were interpreted in terms of the participation of Glu 35 (pK 6.0), Asp 52 (pK 3.5), Asp 48 (pK 4.5), and Asp 66 (pK 1.5). The binding constants of alpha-GlcNAc to hen and turkey lysozymes were the same below pH 3.5 but were different above this pH. The main participant residues in the binding of alpha-GlcNAc were Glu 35, Asp 48, and Asp 66 for hen lysozyme and Glu 35 and Asp 66 for turkey lysozyme. The results obtained here were well explained by the following assumptions: (1) above about pH 4, alpha-GlcNAc binds to hen lysozyme in both alpha- and beta-modes, which correspond to the binding orientation of alpha-GlcNAc and that of beta-GlcNAc, respectively, as determined by X-ray crystallographic studies, but it binds predominantly in the beta-mode below about pH 4, (2) beta-GlcNAc binds to hen and turkey lysozymes predominantly in the beta-mode above about pH 4 and in both alpha- and beta-modes below pH 4, and (3) alpha-GlcNAc binds to turkey lysozyme predominantly in the beta-mode over the whole pH range studied.
Acetylglucosamine↗
Binding of substrate analogs to hen egg-white lysozyme with an ester linkage between Glu 35 and Trp 108.
The interactions of the substrate analogs beta-methyl-GlcNAc, (GlcNAc)2, and (GlcNAc)3 with hen egg-white lysozyme [EC 3.2.1.17] in which an ester linkage had been formed between Glu 35 and Trp 108 (108 ester lysozyme), were studied by the circular dichroic and fluorescence techniques, and were compared with those for intact lysozyme. The binding constants of beta-methyl-GlcNAc and (GlcNAc)2 to 108 ester lysozyme were essentially the same as those for intact lysozyme in the pH range of 1 to 5. Above pH 5, the binding constants of these saccharides to 108 ester lysozyme did not change with pH, while the binding constants to intact lysozyme decreased. This indicates that Glu 35 (pK 6.0 in intact lysozyme) participates in the binding of these saccharides. The extent and direction of the pK shifts of Asp 52 (pK 3.5), Asp 48 (pK 4.4), and Asp 66 (pK 1.3) observed when beta-methyl-GlcNAc is bound to 108 ester lysozyme were the same as those for intact lysozyme. The participation of Asp 101 and Asp 66 in the binding of (GlcNAc)2 to 108 ester lysozyme was also the same as that for intact lysozyme. These findings indicate that the conformations of subsites B and C are not changed by the formation of the ester linkage. On the other hand, the binding constants of (GlcNAc)3 to 108 ester lysozyme were higher than those for intact lysozyme at all pH values studied. This result is interpreted in terms of an increase in the affinity for a GlcNAc residue of subsite D, which is situated near the esterified Glu 35.
Acetylglucosamine↗
Binding of substrate analogues to hen egg-white lysozyme with 2-nitrophenylsulfenylated tryptophan 62.
The pH dependence of the extrinsic circular dichroic (CD) band at 375 nm of hen egg-white lysozyme [EC 3.2.1.17] in which Trp 62 had selectively 2-nitrophenylsulfenylated (NPS-lysozyme) was studied. This pH dependence was interpreted in terms of the participation of Glu 35 (pK 6.2), Asp 101 (pK 4.6), and Asp 66 (pK1.5). The fact that the ionization of Glu 35 affects the extrinsic CD band of the NPS chromophore attached to Trp 62 confirms the presence of a relation between the state of Trp 62 and the ionization state of one of the catalytic groups, Glu 35, in hen lysozyme, as proposed by Ikeda and Hamaguchi (J. Biochem., 74, 221-230 (1973)). The pH dependence of the binding constants of the dimer and trimer of N-acetylglucosamine (GlcNAc) and the beta-methyl glycoside of GlcNAc (beta-methyl-GlcNAc) to NPS-lysozyme were studied by measuring the changes in the extrinsic CD band. The changes in the CD spectrum on the binding of (GlcNAc)3 and (GlcNAc)2 were very similar to each other but were different from that on the binding of beta-methyl-GlcNAc. However, beta-methyl-GlcNAc competitively inhibited the binding of (GlcNAc)2 to NPS-lysozyme. The binding constants of the three saccharides to NPS-lysozyme were much smaller than those for intact lysozyme. The pH dependence of the binding constants of (GlcNAc)2 and (GlcNAc)3 were interpreted in terms of the participation of Glu 35 (pK 6.2), Asp 52 (pK 3.3), Asp 101 (pK 4.6), and Asp 66 (pK 1.5). These pK values are very similar to those for intact lysozyme, as determined by Kuramitsu et al. (J. Biochem., 76, 671-683 (1974); 77, 291-301 (1975). Comparison of the binding constants of Mn2qnd Co2'ons to the catalytic carboxyls of NPS-lysozyme with those to intact lysozyme also indicated that the catalytic site of NPS-lysozyme is scarcely affected by this modification. When (GlcNAc)2 or (GlcNAc)3 is bound to NPS-lysozyme, pK shifts of Glu 35, Asp 101, and Asp 66 occurred in the same directions as for intact lysozyme. In addition, a pK shift of Asp 52, which has not been observed for intact lysozyme, occurred. The participation of Asp 52 was also observed in the binding of beta-methyl-GlcNAc. However, the binding of the monomer to NPS-lysozyme produced no significant pK shifts of Glu 35 and Asp 101, in contrast to the situation for intact lysozyme. These facts indicate a small difference in the binding orientation of the saccharides between the modified and intact lysozymes.
Acetylglucosamine↗
pH dependence of the binding constants of N-acetylglucosamine monomers to hen and turkey egg-white lysozymes.
The binding constants of N-acetylglucosamine (G1cNAc) and its methyl alpha- and beta- glycosides to hen and turkey egg-white lysozymes [EC 3.2.1.17], in the latter of which Asp 101 is replaced by Gly, were determined at various pH values by measuring changes in the circular dichroic (DC) band at 295 nm. The binding of beta-methyl-G1cNAc to turkey and hen lysozymes perturbed the pK value of Glu 35 from 6.0 to 6.5, the pK value of Asp 52 from 3.5 to 3.9, and the pK value of Asp 66 from 1.3 to 0.7. In addition, perturbation of the pK value of Asp 101 from 4.4 to 4.0 was observed in the binding of this saccharide to hen lysozyme. The binding of alpha-methyl-GlcNAc to hen and turkey lysozymes perturbed the pK value of Glu 35 to the alkaline side by about 0.5 pH unit, the pK value of Asp 66 to the acidic side by about 0.5 pH unit, and the pK value (4.4) of an ionizable group to the acidic side by about 0.6 pH unit. The last ionizable group was tentatively assigned to Asp 48. The pK value of Asp 52 was not perturbed by the binding of this saccharide. The pH dependence curves for the binding of GlcNAc to hen and turkey lysozymes were very similar and it was suggested that Asp 48, in addition to Asp 66, Asp 52, and Glu 35, is perturbed by the binding of GlcNAc.
Acetylglucosamine↗