LUMINESCENCE OF DERIVATIVES OF THE AROMATIC AMINO ACIDS

2010 ◽  
pp. 91-92
Keyword(s):  
Amino Acids ◽  
Aromatic Amino Acids ◽  
Derivatives Of

scholarly journals Identification of the Tyrosine- and Phenylalanine-Derived Soluble Metabolomes of Sorghum

2021 ◽  
Vol 12 ◽  
Author(s):  
Jeffrey P. Simpson ◽  
Jacob Olson ◽  
Brian Dilkes ◽  
Clint Chapple
Keyword(s):  
Amino Acids ◽  
Cinnamic Acid ◽  
Aromatic Amino Acids ◽  
Flavonoid Glycosides ◽  
Coumaric Acid ◽  
Biotic And Abiotic Stress ◽  
Proportional Contribution ◽  
Negative Ionization ◽  
Derivatives Of

The synthesis of small organic molecules, known as specialized or secondary metabolites, is one mechanism by which plants resist and tolerate biotic and abiotic stress. Many specialized metabolites are derived from the aromatic amino acids phenylalanine (Phe) and tyrosine (Tyr). In addition, the improved characterization of compounds derived from these amino acids could inform strategies for developing crops with greater resilience and improved traits for the biorefinery. Sorghum and other grasses possess phenylalanine ammonia-lyase (PAL) enzymes that generate cinnamic acid from Phe and bifunctional phenylalanine/tyrosine ammonia-lyase (PTAL) enzymes that generate cinnamic acid and p-coumaric acid from Phe and Tyr, respectively. Cinnamic acid can, in turn, be converted into p-coumaric acid by cinnamate 4-hydroxylase. Thus, Phe and Tyr are both precursors of common downstream products. Not all derivatives of Phe and Tyr are shared, however, and each can act as a precursor for unique metabolites. In this study, 13C isotopic-labeled precursors and the recently developed Precursor of Origin Determination in Untargeted Metabolomics (PODIUM) mass spectrometry (MS) analytical pipeline were used to identify over 600 MS features derived from Phe and Tyr in sorghum. These features comprised 20% of the MS signal collected by reverse-phase chromatography and detected through negative-ionization. Ninety percent of the labeled mass features were derived from both Phe and Tyr, although the proportional contribution of each precursor varied. In addition, the relative incorporation of Phe and Tyr varied between metabolites and tissues, suggesting the existence of multiple pools of p-coumaric acid that are fed by the two amino acids. Furthermore, Phe incorporation was greater for many known hydroxycinnamate esters and flavonoid glycosides. In contrast, mass features derived exclusively from Tyr were the most abundant in every tissue. The Phe- and Tyr-derived metabolite library was also utilized to retrospectively annotate soluble MS features in two brown midrib mutants (bmr6 and bmr12) identifying several MS features that change significantly in each mutant.

Important structural features of 15-residue lactoferricin derivatives and methods for improvement of antimicrobial activity

2002 ◽  
Vol 80 (1) ◽  
pp. 65-74 ◽  
Author(s):  
Morten B Strøm ◽  
Bengt Erik Haug ◽  
Øystein Rekdal ◽  
Merete L Skar ◽  
Wenche Stensen ◽  
...  
Keyword(s):  
Amino Acids ◽  
Antimicrobial Activity ◽  
Structural Parameters ◽  
Aromatic Amino Acids ◽  
Structural Features ◽  
Tryptophan Residue ◽  
Qsar Study ◽  
Modified Peptides ◽  
Bovine Lactoferricin ◽  
Derivatives Of

This review focuses on important structural features affecting the antimicrobial activity of 15-residue derivatives of lactoferricins. Our investigations are based on an alanine-scan of a 15-residue bovine lactoferricin derivative that revealed the absolute necessity of two tryptophan residues for antimicrobial activity. This "tryptophan-effect" was further explored in homologous derivatives of human, caprine, and porcine lactoferricins by the incorporation of one additional tryptophan residue, and by increasing the content of tryptophan in the bovine derivative to five residues. Most of the resulting peptides display a substantial increase in antimicrobial activity. To identify which molecular properties make tryptophan so effective, a series of bovine lactoferricin derivatives were prepared containing non-encoded unnatural aromatic amino acids, which represented various aspects of the physicochemical nature of tryptophan. The results clearly demonstrate that tryptophan is not unique since most of the modified peptides were of higher antimicrobial potency than the native peptide. The size and three-dimensional shape of the inserted "super-tryptophans" are the most important determinants for the high antimicrobial activity of the modified peptides. This review also describes the use of a "soft-modeling" approach in order to identify important structural parameters affecting the antimicrobial activity of modified 15-residue murine lactoferricin derivatives. This QSAR-study revealed that the net charge, charge asymmetry, and micelle affinity of the peptides were the most important structural parameters affecting their antimicrobial activity.Key words: antimicrobial peptides, lactoferricin, non-encoded aromatic amino acids, tryptophan.

19F nuclear magnetic resonance studies of the interaction of inhibitors with chymotrypsin. Ring-fluorinated derivatives of N-trifluoroacetylphenylalanine

1978 ◽  
Vol 31 (10) ◽  
pp. 2179 ◽  
Author(s):  
M Tsavalos ◽  
BC Nicholson ◽  
TM Spotswood
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Active Site ◽  
Enzyme Inhibitor ◽  
Aromatic Amino Acids ◽  
Binding Parameters ◽  
Magnetic Resonance Studies ◽  
Derivatives Of

The complexes formed between chymotrypsin and the doubly fluorine- labelled inhibitors, o-, m- and p-fluoro-N-trifluoroacetyl-D- phenylalanine and 2,4-difluoro-N-trifluoroacetyl-D-phenylalanine, have been characterized by 19F N.M.R. spectroscopy and binding parameters, ΔB and KI, have been derived. The results confirm the importance of the amido binding site in orienting aromatic amino acids at the active site of chymotrypsin. Changes in ΔB, the change in chemical shift of the enzyme-bound inhibitor, are shown to be a very sensitive probe of enzyme-inhibitor interactions.

The Efficient Preparation of Radiolabeled Aromatic Amino Acids via Cu-Mediated Radiofluorination using Ni-complexes

2019 ◽  
Author(s):  
A Craig ◽  
N Kolks ◽  
E Urusova ◽  
BD Zlatopolskiy ◽  
B Neumaier
Keyword(s):  
Amino Acids ◽  
Aromatic Amino Acids
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