scholarly journals Amino acids and peptides. X. Leu-enkephalin analogues containing a fluorinated aromatic amino acid.

1989 ◽  
Vol 37 (3) ◽  
pp. 826-828 ◽  
Author(s):  
Mitsuko MAEDA ◽  
Koichi KAWASAKI ◽  
Joe WATANABE ◽  
Hiroshi KANETO
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aromatic Amino Acid ◽  
Enkephalin Analogues

scholarly journals Human transferrin receptor internalization is partially dependent upon an aromatic amino acid on the cytoplasmic domain.

1990 ◽  
Vol 1 (4) ◽  
pp. 369-377 ◽  
Author(s):  
T E McGraw ◽  
F R Maxfield
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Rate Constant ◽  
Transferrin Receptor ◽  
Aromatic Amino Acid ◽  
Opposite Polarity ◽  
Receptor Internalization ◽  
Aromatic Side Chain ◽  
Human Transferrin ◽  
Human Transferrin Receptor

The objective of this work is to identify the elements of the human transferrin receptor that are involved in receptor internalization, intracellular sorting, and recycling. We have found that an aromatic side chain at position 20 on the cytoplasmic portion of the human transferrin receptor is required for efficient internalization. The wild-type human transferrin receptor has a tyrosine at this position. Replacement of the Tyr-20 with an aromatic amino acid does not alter the rate constant of internalization, whereas substitution with the nonaromatic amino acids serine, leucine, or cysteine reduces the internalization rate constant approximately three-fold. These results are consistent with similar studies of other receptor systems that have also documented the requirement for a tyrosine in rapid internalization. The amino terminus of the transferrin receptor is cytoplasmic, with the tyrosine 41 amino acids from the membrane. These two features distinguish the transferrin receptor from the other membrane proteins for which the role of tyrosine in internalization has been examined, because these proteins have the opposite polarity with respect to the membrane and because the tyrosines are located closer to the membrane (within 25 amino acids). The externalization rate for the recycling of the transferrin receptor is not altered by any of these substitutions, demonstrating that the aromatic amino acid internalization signal is not required for the efficient exocytosis of internalized receptor.

Selective Chemical Deuteration of Aromatic Amino Acids: A Retrospective

1997 ◽  
Author(s):  
K.S. Matthews ◽  
R. Matthews
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aromatic Amino Acid ◽  
Protein Hydrolysate ◽  
Aromatic Amino Acids ◽  
Cellular Protein ◽  
Target Protein ◽  
Chemical Methods ◽  
Lactose Repressor ◽  
Selective Deuteration

In 1970 when we began post-doctoral work in the laboratory of Professor Oleg Jardetzky, selective deuteration of proteins to limit the number of protons present in the system for subsequent analysis was a newly developed and effective technique for NMR exploration of protein structure (Crespi et al., 1968; Markley et al., 1968). This approach allowed more facile assignment of specific resonances and generated the potential to follow the spectroscopic behavior of protons for a specific amino acid sidechain over a broad range of conditions. The primary method for labeling at that time involved growth of microorganisms (generally bacteria or algae) in D2O, followed by isolation of the deuteratedamino acids from a cellular protein hydrolysate. The amino acids isolated were, therefore, completely deuterated. Selective deuteration of a target protein was achieved by growing the producing organism on a mixture of completely deuterated and selected protonated amino acids under conditions that minimized metabolic interconversion of the amino acids. In one-dimensional spectra, aromatic amino acid resonances occur well downfield of the aliphatic resonances, and this region can therefore be examined somewhat independently by utilizing a single protonated aromatic amino acid to simplify the spectrum of the protein. However, the multiple spectral lines generated by aromatic amino acids can be complex and overlapping, precluding unequivocal interpretation. To address this complication, chemical methods were developed to both completely and selectively deuterate side chains of the aromatic amino acids, thereby avoiding the costly necessity of growing large volumes of microorganisms in D2O and subsequent tedious isolation procedures. In addition, selective deuteration of the amino acids simplified the resonance patterns and thereby facilitated assignment and interpretation of spectra. The methods employed were based on exchange phenomena reported in the literature and generated large quantities of material for use in growth of microorganisms for subsequent isolation of selectively labeled protein (Matthews et al., 1977a). The target protein for incorporation of the selectively deuterated aromatic amino acids generated by these chemical methods was the lactose repressor protein from Escherichia coli, and greatly simplified spectra of this 150,000 D protein were produced by this approach.

scholarly journals Decoding the Complex Crossroad of Tryptophan Metabolic Pathways

2022 ◽  
Vol 23 (2) ◽  
pp. 787
Author(s):  
Giada Mondanelli ◽  
Claudia Volpi ◽  
Ciriana Orabona
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Metabolic Pathways ◽  
Aromatic Amino Acid ◽  
Living Cells ◽  
Cellular Homeostasis

Among the 20 amino acids needed for protein synthesis, Tryptophan (Trp) is an aromatic amino acid fundamental not only for the synthesis of the major components of living cells (namely, the proteins), but also for the maintenance of cellular homeostasis [...]

scholarly journals Histidine Degradation via an Aminotransferase Increases the Nutritional Flexibility of Candida glabrata

2014 ◽  
Vol 13 (6) ◽  
pp. 758-765 ◽  
Author(s):  
Sascha Brunke ◽  
Katja Seider ◽  
Martin Ernst Richter ◽  
Sibylle Bremer-Streck ◽  
Shruthi Ramachandra ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aromatic Amino Acid ◽  
Candida Glabrata ◽  
Genomic Structure ◽  
Aromatic Amino Acids ◽  
Sole Source ◽  
Upstream Region ◽  
Content Type ◽  
Aromatic Amino Acid Aminotransferase

ABSTRACTThe ability to acquire nutrients during infections is an important attribute in microbial pathogenesis. Amino acids are a valuable source of nitrogen if they can be degraded by the infecting organism. In this work, we analyzed histidine utilization in the fungal pathogen of humansCandida glabrata. Hemiascomycete fungi, likeC. glabrataorSaccharomyces cerevisiae, possess no gene coding for a histidine ammonia-lyase, which catalyzes the first step of a major histidine degradation pathway in most other organisms. We show thatC. glabratainstead initializes histidine degradation via the aromatic amino acid aminotransferase Aro8. AlthoughARO8is also present inS. cerevisiaeand is induced by extracellular histidine, the yeast cannot use histidine as its sole nitrogen source, possibly due to growth inhibition by a downstream degradation product. Furthermore,C. glabratarelies only on Aro8 for phenylalanine and tryptophan utilization, sinceARO8, but not its homologueARO9, was transcriptionally activated in the presence of these amino acids. Accordingly, anARO9deletion had no effect on growth with aromatic amino acids. In contrast, inS. cerevisiae,ARO9is strongly induced by tryptophan and is known to support growth on aromatic amino acids. Differences in the genomic structure of theARO9gene betweenC. glabrataandS. cerevisiaeindicate a possible disruption in the regulatory upstream region. Thus, we show that, in contrast toS. cerevisiae,C. glabratahas adapted to use histidine as a sole source of nitrogen and that the aromatic amino acid aminotransferase Aro8, but not Aro9, is the enzyme required for this process.

Amino Acid Profile and Aromatic Amino Acid Concentration in Total Parenteral Nutrition: Effect on Growth, Protein Metabolism and Aromatic Amino Acid Metabolism in the Neonatal Piglet

1994 ◽  
Vol 87 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Linda J. Wykes ◽  
James D. House ◽  
Ronald O. Ball ◽  
Paul B. Pencharz
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Parenteral Nutrition ◽  
Human Milk ◽  
Total Parenteral Nutrition ◽  
Aromatic Amino Acid ◽  
Nitrogen Retention ◽  
Aromatic Amino Acids ◽  
The Other ◽  
Constant Infusion

1. The protein and amino acid utilization of two commercially available amino acid solutions, one egg-patterned (Vamin), the other human-milk-patterned (Vaminolact), were studied in piglets receiving total parenteral nutrition. It was hypothesized that Vaminolact was deficient in total aromatic amino acids, so a third group received a human-milk-patterned amino acid solution with added phenylalanine. 2. The piglets were on total parenteral nutrition for 8 days from day 2 or 3 of life. They all received a total energy intake of 1040 kJ day−1 kg−1 with macro-nutrient intakes of 14.6g of amino acid, 27.4 g of glucose and 9.4 g of fat day−1 kg−1. 3. Nitrogen balances were performed on days 3-8 of total parenteral nutrition. On day 8 a primed constant infusion of (1-14C]-phenylalanine was given to measure phenylalanine flux and fractional conversion to tyrosine. Transamination catabolites of phenylalanine and tyrosine were measured in urine on day 7. 4. The piglets receiving Vaminolact gained significantly less weight (0.86 kg compared with 1.18 kg for Vamin and 1.20 kg for phenylalanine-supplemented Vaminolact; P < 0.02) and nitrogen (1435 mg day−1 kg−1 compared with 1601 mg and 1836 mg day−1 kg−1 for the other groups; P < 0.0001). 5. The piglets receiving Vamin had high plasma phenylalanine levels (2234 μmol/l compared with 156 μmol/l for Vaminolact and 399 μmol for phenylalanine-supplemented Vaminolact; P < 0.0001). Those receiving Vamin also had an elevated excretion of phenylalanine transamination metabolites and low plasma lysine levels. Phenylalanine flux was highest in the Vamin group, intermediate in the phenylalanine-supplemented Vaminolact group and lowest in the Vaminolact group. 6. We conclude that Vaminolact is limiting in aromatic amino acids and that the addition of phenylalanine to the level in Vamin significantly improves growth and nitrogen retention; however, increasing the phenylalanine content of total parenteral nutrition is not the most metabolically suitable way to provide aromatic amino acids in neonatal total parenteral nutrition.

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