Alkaloids of the Australian Rutaceae: Evodia xanthoxyloides F.Muell. V. A note on the constitution of evolidine

1955 ◽  
Vol 8 (4) ◽  
pp. 552 ◽  
Author(s):  
RM Curtis
Keyword(s):  
Amino Acid ◽  
Amino Acid Residues ◽  
Cyclic Structure ◽  
New Formula

Evolidine, formerly described as an alkaloid, is shown to be a peptide. A new formula C38H58O9N8 having a cyclic structure and containing seven amino acid residues is proposed.

Melanin Concentrating Hormone Analogs: Contraction of the Cyclic Structure. III. CD Spectroscopic Study

1992 ◽  
Vol 57 (3) ◽  
pp. 614-620
Author(s):  
Ivo Frič ◽  
Michal Lebl ◽  
Victor J. Hruby
Keyword(s):  
Amino Acid ◽  
Spectroscopic Study ◽  
Spectral Properties ◽  
Membered Ring ◽  
Helical Conformation ◽  
Amino Acid Residues ◽  
Cyclic Structure ◽  
Cd Spectra ◽  
Melanin Concentrating Hormone ◽  
Hormone Analogs

A comparison of the CD spectra of MCH analogs differing in length but containing a heterodetic ring of the same size (compounds I, IV and VII or III, VI and IX) reveals that a conformational change occurs upon elongating the peptide chain from thirteen to seventeen amino-acid residues. The 5-17 fragments appear to prefer a β-turn conformation, whereas the 1-17 full-sequence peptides prefer α-helical conformation. Peptides containing seventeen-membered ring exhibit greater conformational adaptability (the incorporation of their cyclic moiety into an ordered conformation being easier) than those containing a twenty-six-membered ring. Spectral properties of the twenty-three-membered heterodetic ring in peptides II and V indicate that they do not possess highly ordered conformation.

Substrate Recognition by Vitamin K-Dependent Carboxylase

1987 ◽  
Vol 57 (01) ◽  
pp. 017-019 ◽  
Author(s):  
Magda M W Ulrich ◽  
Berry A M Soute ◽  
L Johan M van Haarlem ◽  
Cees Vermeer
Keyword(s):  
Amino Acid ◽  
Vitamin K ◽  
Substrate Recognition ◽  
Bovine Liver ◽  
Amino Acid Residues

SummaryDecarboxylated osteocalcins were prepared and purified from bovine, chicken, human and monkey bones and assayed for their ability to serve as a substrate for vitamin K-dependent carboxylase from bovine liver. Substantial differences were observed, especially between bovine and monkey d-osteocalcin. Since these substrates differ only in their amino acid residues 3 and 4, it seems that these residues play a role in the recognition of a substrate by hepatic carboxylase.

Statistical Force-Field for Structural Modeling Using Chemical Cross-Linking/mass Spectrometry Distance Constraints

2018 ◽  
Author(s):  
Allan J. R. Ferrari ◽  
Fabio C. Gozzo ◽  
Leandro Martinez
Keyword(s):  
Mass Spectrometry ◽  
Amino Acid ◽  
Force Field ◽  
Protein Structures ◽  
Protein Structure Determination ◽  
Structural Modeling ◽  
Cross Linking ◽  
Amino Acid Residues ◽  
Distance Constraints ◽  
Chemical Cross Linking

<div><p>Chemical cross-linking/Mass Spectrometry (XLMS) is an experimental method to obtain distance constraints between amino acid residues, which can be applied to structural modeling of tertiary and quaternary biomolecular structures. These constraints provide, in principle, only upper limits to the distance between amino acid residues along the surface of the biomolecule. In practice, attempts to use of XLMS constraints for tertiary protein structure determination have not been widely successful. This indicates the need of specifically designed strategies for the representation of these constraints within modeling algorithms. Here, a force-field designed to represent XLMS-derived constraints is proposed. The potential energy functions are obtained by computing, in the database of known protein structures, the probability of satisfaction of a topological cross-linking distance as a function of the Euclidean distance between amino acid residues. The force-field can be easily incorporated into current modeling methods and software. In this work, the force-field was implemented within the Rosetta ab initio relax protocol. We show a significant improvement in the quality of the models obtained relative to current strategies for constraint representation. This force-field contributes to the long-desired goal of obtaining the tertiary structures of proteins using XLMS data. Force-field parameters and usage instructions are freely available at http://m3g.iqm.unicamp.br/topolink/xlff <br></p></div><p></p><p></p>

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