ChemInform Abstract: Syntheses of Chiral Bishomodiazacalix[4]arenes Incorporating Amino Acid Residues: Molecular Recognition for Racemic Ammonium Ions by the Macrocycles Possessing Tyrosine Residues.

ChemInform ◽  
2010 ◽  
Vol 31 (27) ◽  
pp. no-no
Author(s):  
Kazuaki Ito ◽  
Takanori Ohta ◽  
Yoshihiro Ohba ◽  
Tyo Sone
Keyword(s):  
Amino Acid ◽  
Molecular Recognition ◽  
Amino Acid Residues ◽  
Ammonium Ions ◽  
Tyrosine Residues

scholarly journals Inactivation of aspartyl proteinases by butane-2,3-dione. Modification of tryptophan and tyrosine residues and evidence against reaction of arginine residues

1981 ◽  
Vol 193 (1) ◽  
pp. 55-65 ◽  
Author(s):  
J C Gripon ◽  
T Hofmann
Keyword(s):  
Amino Acid ◽  
Arginine Residue ◽  
Penicillium Roqueforti ◽  
Amino Acid Residues ◽  
Prolonged Incubation ◽  
Tyrosine Residues ◽  
Arginine Residues ◽  
Structural Breakdown ◽  
Methionine Residues ◽  
Aspartyl Proteinases

Butane-2,3-dione inactivates the aspartyl proteinases from Penicillium roqueforti and Penicillium caseicolum, as well as pig pepsin, penicillopepsin and Rhizopus pepsin, at pH 6.0 in the presence of light but not in the dark. The inactivation is due to a photosensitized modification of tryptophan and tyrosine residues. In the dark none of the amino acid residues, not even arginine residues, is modified even after several days. In the light one arginine residue in pig pepsin is lost at a rate that is comparable with the rate of inactivation; however, the loss of the single arginine residue in the aspartyl proteinase of P. roqueforti and the second arginine residue of pig pepsin is slower than the loss of activity; penicillopepsin is devoid of arginine. Loss of most of the activity is accompanied by the following amino acid losses: P. roqueforti aspartyl proteinase, about two tryptophan and six tyrosine residues; penicillopepsin, about two tryptophan and three tyrosine residues; pig pepsin, about four tryptophan and most of the tyrosine residues. Modification of histidine residues was too slow to contribute to inactivation. None of the other residues, including half-cystine and methionine residues (when present), was modified even after prolonged incubation. The inactivation of P. roqueforti aspartyl proteinase and pig pepsin appears due to non-specific modification of several residues. With penicillopepsin, however, the reaction is more limited and initially affects only those tryptophan and tyrosine residues that lie in the active-site groove. In the presence of pepstatin the rate of inactivation is considerably diminished. After prolonged reaction a general structural breakdown occurs.

scholarly journals Amino acid sequences C-terminal to the cross-links in bovine elastin

1980 ◽  
Vol 185 (3) ◽  
pp. 611-616 ◽  
Author(s):  
K M Baig ◽  
M Vlaovic ◽  
R A Anwar
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequences ◽  
Amino Acid Residues ◽  
Tyrosine Residues ◽  
Lysine Residues ◽  
Cross Links ◽  
The Cross

All the desmosine-containing elastolytic peptides of bovine ligamentum-nuchae elastin have now been examined for amino acid sequences C-terminal to the cross-links. In addition, amino acid residues C-terminal to lysine residues in bovine tropoelastin were also examined. No tyrosine C-terminal to cross-links in bovine elastin or C-terminal to lysine in tropoelastin was detected. Apparently all the tyrosine residues C-terminal to lysine residues in pig tropoelastin are replaced with phenylalanine in bovine tropoelastin. All the data presented are consistent with the scheme proposed for the formation of desmosine and isodesmosine cross-links of elastin by Gerber & Anwar [(1975) Biochem. J. 149, 685-695].

scholarly journals Cryo-EM structure of the tetracycline resistance protein TetM in complex with a translating ribosome at 3.9-Å resolution

2015 ◽  
Vol 112 (17) ◽  
pp. 5401-5406 ◽  
Author(s):  
Stefan Arenz ◽  
Fabian Nguyen ◽  
Roland Beckmann ◽  
Daniel N. Wilson
Keyword(s):  
Electron Microscopy ◽  
Amino Acid ◽  
16S Rrna ◽  
Binding Site ◽  
Tetracycline Resistance ◽  
Small Subunit ◽  
Amino Acid Residues ◽  
Tyrosine Residues ◽  
Cryo Electron Microscopy ◽  
Resistance Protein

Ribosome protection proteins (RPPs) confer resistance to tetracycline by binding to the ribosome and chasing the drug from its binding site. Current models for RPP action are derived from 7.2- to 16-Å resolution structures of RPPs bound to vacant or nontranslating ribosomes. Here we present a cryo-electron microscopy reconstruction of the RPP TetM in complex with a translating ribosome at 3.9-Å resolution. The structure reveals the contacts of TetM with the ribosome, including interaction between the conserved and functionally critical C-terminal extension of TetM with a unique splayed conformation of nucleotides A1492 and A1493 at the decoding center of the small subunit. The resolution enables us to unambiguously model the side chains of the amino acid residues comprising loop III in domain IV of TetM, revealing that the tyrosine residues Y506 and Y507 are not responsible for drug-release as suggested previously but rather for intrafactor contacts that appear to stabilize the conformation of loop III. Instead, Pro509 at the tip of loop III is located directly within the tetracycline binding site where it interacts with nucleotide C1054 of the 16S rRNA, such that RPP action uses Pro509, rather than Y506/Y507, to directly dislodge and release tetracycline from the ribosome.

Potentiometrische und spektrophotometrische Titrationen der Nukleoproteide und Proteine von Mutanten und Wildstämmen des Tabakmosaikvirus TMV / Potentiometric and Spectrophotometric Titrations of the Nucleoproteins and Proteins of Tobacco Mosaic Virus Strains and Mutants

1972 ◽  
Vol 27 (4) ◽  
pp. 427-444 ◽  
Author(s):  
Gisela Paulsen
Keyword(s):  
Amino Acid ◽  
Structural Changes ◽  
Lead Ions ◽  
Tyrosine Residue ◽  
Amino Acid Residues ◽  
Binding Studies ◽  
Tyrosine Residues ◽  
Ph Values ◽  
Titration Curves ◽  
Spectrophotometric Titrations

The position of acidic, basic and phenolic amino acid residues of nucleoproteins and proteins of the TMV strains vulgare (and mutants of vulgare), dahlemense, and U 2 were determined by comparative potentiometric and spectrophotometric titrations in order to obtain more precise information about the interactions of proteins.In the nucleoproteins of all these mutants only 8 carboxylgroups of 16 (vulgare, A 14, Ni 1927 and U 2) and 8 of 15 (flavum, Ni 116, Ni 109 and Ni 606) can be titrated. Thus it is concluded that only these 8 groups are situated near the surface.The differences in the titration curves, measured at I=0.1 and I=0.02 show that one amino acid with pK 5.2 is titrated in vulgare but not flavum, Ni 116 and Ni 606. The titration curves of the mutant proteins differ from one another and from that of vulgare between pH 7 and 6 and this is probably due to aggregation which starts for each protein at different pH values. In addition, the differences in titration curves at pH values 4.5 are probably due structural changes.Also the titration curves of the strain proteins of vulgare, dahlemense and U 2 are different. The first binding of protons during the titration of the proteins occurs before pH 7 for U 2, about pH 7 for vulgare, and at pH 6.6 for dahlemense. Opalescence and sedimentation values indicate that aggregation takes place in the same sequence. At pH values >5 vulgare protein binds more protons than dahlemense and fewer than U 2. Due to the isoelectric state the U 2 protein precipitates at pH 5.5 (nucleoprotein at pH 4.1), dahlemense protein does not precipitate (although nucleoprotein does precipitate at pH 3.15) and the vulgare nucleoprotein and protein precipitate at pH 3.9.Spectrophotometric titrations indicate that two of 4 tyrosine residues are ionized in vulgare and mutant nucleoproteins (except Ni 2068 where 1.2 of 3 tyrosine residues are ionized). The dissociation of the first proton of a tyrosine residue begins with the depolymerization of the nucleoprotein which is not completed until the titration end point is reached (pH 12.6). The ionization of the tyrosine residues begins at lower pH values in proteins than in nucleoproteins and, furthermore, the protein contains an additional ionized tyrosine residue.In the nucleoprotein and protein of U 2 4.2 of 6 tyrosine residues are titrated whereas in dahlemense 2.3 and 3.8 tyrosine residues are titrated in nucleoprotein and protein, respectively.Binding studies with labelled lead ions show that vulgare, related mutants, and U 2 bind two lead ions per subunit whereas dahlemense binds 2.5. The comparison of all results shows that a constant number of acidic amino acid residues must be on the surface of the TMV particle in order to obtain a stable TMV nucleoprotein. Furthermore, two intermolecular interactions between carboxyl-carboxylate groups must be present for the aggregation of proteins to occur.

scholarly journals The dimerization of half-molecule fragments of transferrin

1988 ◽  
Vol 251 (3) ◽  
pp. 849-855 ◽  
Author(s):  
J Williams ◽  
K Moreton
Keyword(s):  
Amino Acid ◽  
Molecular Recognition ◽  
Amino Acid Residues ◽  
X Ray ◽  
X Ray Crystallography ◽  
Recognition Sites ◽  
Terminal Fragment

Partial proteolysis was used to prepare half-molecule fragments of hen ovotransferrin. N-Terminal and C-terminal fragments associate to form an N-terminal fragment-C-terminal fragment dimer. Variant forms of the N- and C-terminal fragments can be prepared in which a few amino acid residues are lacking from the C-terminal ends of the fragments. These variant fragments are partially or completely unable to associate; the suggestion that the molecular recognition sites are located in these C-terminal stretches of the N-terminal half-molecule (320-332) and of the C-terminal half-molecule (683-686) is in agreement with X-ray-crystallography data for human lactotransferrin [Anderson, Baker, Dodson, Norris, Rumball, Waters & Baker (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 1769-1773].

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