scholarly journals The Uniqueness of Tryptophan in Biology: Properties, Metabolism, Interactions and Localization in Proteins

2020 ◽  
Vol 21 (22) ◽  
pp. 8776 ◽  
Author(s):  
Sailen Barik
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Structural Features ◽  
Ring Structure ◽  
Side Chain ◽  
Aromatic Side Chain ◽  
Single Ring ◽  
Energy Consuming ◽  
Animal Diet ◽  
Abundant Amino Acid

Tryptophan (Trp) holds a unique place in biology for a multitude of reasons. It is the largest of all twenty amino acids in the translational toolbox. Its side chain is indole, which is aromatic with a binuclear ring structure, whereas those of Phe, Tyr, and His are single-ring aromatics. In part due to these elaborate structural features, the biosynthetic pathway of Trp is the most complex and the most energy-consuming among all amino acids. Essential in the animal diet, Trp is also the least abundant amino acid in the cell, and one of the rarest in the proteome. In most eukaryotes, Trp is the only amino acid besides Met, which is coded for by a single codon, namely UGG. Due to the large and hydrophobic π-electron surface area, its aromatic side chain interacts with multiple other side chains in the protein, befitting its strategic locations in the protein structure. Finally, several Trp derivatives, namely tryptophylquinone, oxitriptan, serotonin, melatonin, and tryptophol, have specialized functions. Overall, Trp is a scarce and precious amino acid in the cell, such that nature uses it parsimoniously, for multiple but selective functions. Here, the various aspects of the uniqueness of Trp are presented in molecular terms.

MATHEMATICAL MODELS FOR THE SYNTHESIS OF PLANT-BASED COMPOSITIONS WITH IMPROVED AMINO ACID COMPOSITION

2021 ◽  
Author(s):  
Irina Gaivoronskaya ◽  
Valenitna Kolpakova
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Mathematical Models ◽  
Functional Properties ◽  
Amino Nitrogen ◽  
Essential Amino Acids ◽  
Major Allergen ◽  
Structural Features ◽  
Covalent Bonds ◽  
Pea Protein

The aim of the work was to optimize the process of obtaining multicomponent protein compositions with high biological value and higher functional properties than the original vegetable protein products. Was realized studies to obtain biocomposites on the base of pea protein-oat protein and pea protein-rice protein. Developed composites were enriched with all limited amino acids. For each of the essential amino acids, the amino acid score was 100% and higher. Protein products used in these compositions are not in major allergen list, which allows to use these compositions in allergen-free products and specialized nutrition. To determine biosynthesis parameters for compositions from pea protein and various protein concentrates with the use of transglutaminase enzyme, was studied effect of concentration and exposition time on the amount of amino nitrogen released during the reaction. Decreasing of amino nitrogen in the medium indicated the occurrence of a protein synthesis reaction with the formation of new covalent bonds. Were determined optimal parameters of reaction: the hydromodule, the exposure time, the concentration of EP of the preparation, were obtained mathematical models. Studies on the functional properties of composites, the physicochemical properties of the proteins that make up their composition, and structural features will make it possible to determine the uses in the manufacture of food products based on their ability to bind fat, water, form foam, gels, and etc.

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.

Isolation and characterization of some novel genes of the apolipoprotein A-I family in Japanese eel, Anguilla japonica

2011 ◽  
Vol 6 (4) ◽  
pp. 545-557 ◽  
Author(s):  
Malay Choudhury ◽  
Takahiro Oku ◽  
Shoji Yamada ◽  
Masaharu Komatsu ◽  
Keita Kudoh ◽  
...  
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Consensus Sequence ◽  
Structural Features ◽  
Lipid Binding ◽  
Japanese Eel ◽  
Amino Acid Sequences ◽  
Novel Genes ◽  
Isolation And Characterization

AbstractApolipoproteins such as apolipoprotein (apo) A-I, apoA-IV, and apoE are lipid binding proteins synthesized mainly in the liver and the intestine and play an important role in the transfer of exogenous or endogenous lipids through the circulatory system. To investigate the mechanism of lipid transport in fish, we have isolated some novel genes of the apoA-I family, apoIA-I (apoA-I isoform) 1–11, from Japanese eel by PCR amplification. Some of the isolated genes of apoIA-I corresponded to 28kDa-1 cDNAs which had already been deposited into the database and encoded an apolipoprotein with molecular weight of 28 kDa in the LDL, whereas others seemed to be novel genes. The structural organization of all apoIA-Is consisted of four exons separated by three introns. ApoIA-I10 had a total length of 3232 bp, whereas other genes except for apoIA-I9 ranged from 1280 to 1441 bp. The sequences of apoIA-Is at the exon-intron junctions were mostly consistent with the consensus sequence (GT/AG) at exon-intron boundaries, whereas the sequences of 3′ splice acceptor in intron 1 of apoIA-I1-7 were (AC) but not (AG). The deduced amino acid sequences of all apoIA-Is contained a putative signal peptide and a propeptide of 17 and 5 amino acid residues, respectively. The mature proteins of apoIA-I1-3, 7, and 8 consisted of 237 amino acids, whereas those of apoIA-I4-6 consisted of 239 amino acids. The mature apoIA-I10 sequence showed 65% identity to amino acid sequence of apoIA-I11 which was associated with an apolipoprotein with molecular weight of 23 kDa in the VLDL. All these mature apoIA-I sequences satisfied the common structural features depicted for the exchangeable apolipoproteins such as apoA-I, apoA-IV, and apoE but apoIA-I11 lacked internal repeats 7, 8, and 9 when compared with other members of apoA-I family. Phylogenetic analysis showed that these novel apoIA-Is isolated from Japanese eel were much closer to apoA-I than apoA-IV and apoE, suggesting new members of the apoA-I family.

scholarly journals Structural basis for divergent and convergent evolution of catalytic machineries in plant aromatic amino acid decarboxylase proteins

2020 ◽  
Vol 117 (20) ◽  
pp. 10806-10817 ◽  
Author(s):  
Michael P. Torrens-Spence ◽  
Ying-Chih Chiang ◽  
Tyler Smith ◽  
Maria A. Vicent ◽  
Yi Wang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Convergent Evolution ◽  
Structural Features ◽  
Divergent Evolution ◽  
Structural Basis ◽  
Acid Decarboxylase ◽  
Substrate Selectivity ◽  
Amino Acid Decarboxylase ◽  
Catalytic Mechanisms

Radiation of the plant pyridoxal 5′-phosphate (PLP)-dependent aromatic l-amino acid decarboxylase (AAAD) family has yielded an array of paralogous enzymes exhibiting divergent substrate preferences and catalytic mechanisms. Plant AAADs catalyze either the decarboxylation or decarboxylation-dependent oxidative deamination of aromatic l-amino acids to produce aromatic monoamines or aromatic acetaldehydes, respectively. These compounds serve as key precursors for the biosynthesis of several important classes of plant natural products, including indole alkaloids, benzylisoquinoline alkaloids, hydroxycinnamic acid amides, phenylacetaldehyde-derived floral volatiles, and tyrosol derivatives. Here, we present the crystal structures of four functionally distinct plant AAAD paralogs. Through structural and functional analyses, we identify variable structural features of the substrate-binding pocket that underlie the divergent evolution of substrate selectivity toward indole, phenyl, or hydroxyphenyl amino acids in plant AAADs. Moreover, we describe two mechanistic classes of independently arising mutations in AAAD paralogs leading to the convergent evolution of the derived aldehyde synthase activity. Applying knowledge learned from this study, we successfully engineered a shortened benzylisoquinoline alkaloid pathway to produce (S)-norcoclaurine in yeast. This work highlights the pliability of the AAAD fold that allows change of substrate selectivity and access to alternative catalytic mechanisms with only a few mutations.

The Influence of the Aromatic Amino Acid Side-Chains on the Sign of the Soret Cotton Effect in Chironomus Hemoglobin (CTT III)

1972 ◽  
Vol 27 (5) ◽  
pp. 530-532 ◽  
Author(s):  
Jörg Fleischhauer ◽  
Axel Wollmer
Keyword(s):  
Amino Acid ◽  
Aromatic Amino Acid ◽  
Cotton Effect ◽  
Side Chain ◽  
Side Chains ◽  
Aromatic Side Chain ◽  
Rotational Strength ◽  
Amino Acid Side Chains ◽  
Atomic Coordinates

The origin of the positive Soret Cotton effect of myoglobin was calculated by Hsu and WOODY on the basis of a mechanism taking into account the coupling of the Soret and aromatic side-chain π—π* transitions. HUBER and coworkers have worked out the atomic coordinates of a monomeric insect hemoglobin which exhibits a negative Soret Cotton effect.It seemed of some importance to examine the capability of this mechanism to explain the observed inversion of sign. The calculations resulted indeed in a negative total rotational strength (—0,2 DBM), the main contributions arising from phenylalanine residues.

RP-HPLC Determination of Tiger Nut and Orgeat Amino Acid Contents

2005 ◽  
Vol 11 (1) ◽  
pp. 33-40 ◽  
Author(s):  
L. Bosch ◽  
A. Alegría ◽  
R. Farré
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Profile ◽  
African Origin ◽  
Rp Hplc ◽  
Precision And Accuracy ◽  
Amino Acid Contents ◽  
Tiger Nuts ◽  
Abundant Amino Acid

The amino acid profile of 11 samples of tiger nuts ( Cyperus esculentusL.) grown in the area of “L'Horta Nord” in Valencia (Spain) and one sample of African origin were determined, along with the amino acid contents of 10 samples of natural orgeat from Valencia. Protein was hydrolysed by hydrochloric acid at 110 °C for 23 h, and amino acids were derivatised with AQC and determined by RP-HPLC with fluorescence detection. The chromatographic conditions were optimised. The analytical parameters (detection and quantification limits, precision and accuracy) showed the method to be sufficiently sensitive and reproducible for determining amino acids resistant to acid hydrolysis in tiger nuts and orgeat. Arginine was the most abundant amino acid in both tiger nuts and orgeat and the lowest contents corresponding to histidine and tyrosine. The essential amino acid contents of tiger nuts and orgeat protein were greater than those proposed in the protein standard for adults by the FAO/WHO, with the exception of histidine. No significant differences were found among the arginine, lysine and isoleucine amino acid contents in tiger nuts from Valencia, Alboraya and Alm‡ssera; nor were they found among amino acids in tiger nuts from Valencia and Alm‡ssera, with the exception of tyrosine.

Interactions of neutral and acidic amino acids in renal tubular transport

1962 ◽  
Vol 202 (3) ◽  
pp. 577-583 ◽  
Author(s):  
William A. Webber
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Plasma Concentrations ◽  
Side Chain ◽  
Neutral Amino Acids ◽  
Acidic Amino Acids ◽  
Renal Tubular Reabsorption ◽  
Renal Tubular Transport ◽  
Renal Tubular ◽  
Amino Acid Concentrations

The effects of intravenous infusions of a variety of neutral and acidic amino acids on the plasma concentrations and excretions of naturally occurring amino acids were studied in dogs. Conventional clearance techniques were used, and the amino acid concentrations were determined by ion exchange column chromatography. Infusion of either l-glutamic acid or l-aspartic acid caused a gross increase in the plasma concentration and excretion of the other. Infusions of neutral amino acids including glycine, l-alanine, l-leucine, l-methionine, l-proline, and l-phenylalanine caused some minor changes in the endogenous plasma amino acid concentrations. They produced increases in the excretion of other neutral amino acids and, in some cases, of acidic and basic amino acids as well. In general, amino acids with long side chains were most effective in inhibiting reabsorption while cyclic side-chain compounds were less effective. There appear to be at least three somewhat separable mechanisms for renal tubular reabsorption of amino acids in dogs.

Decomposition of copper – amino acid complexes by oxalic acid dihydrate

2012 ◽  
Vol 90 (6) ◽  
pp. 557-559 ◽  
Author(s):  
Yi Liu ◽  
Genguang Jia ◽  
Xin Ling ◽  
Nuo Lan ◽  
Youguang Zheng ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Oxalic Acid ◽  
Free Amino Acid ◽  
Free Amino ◽  
Environmentally Friendly ◽  
Side Chain ◽  
Acid Complex ◽  
Oxalic Acid Dihydrate ◽  
Amino Acid Complex

A facile approach to the synthesis of some side-chain-protected amino acids via oxalic acid dihydrate as the copper sequestering reagent is presented. The copper in the amino acid complex reacted with oxalic acid dihydrate to form insoluble cupric oxalate, with the free amino acid released. Compared with conventional methods, this method is convenient, inexpensive, and environmentally friendly.

Predicting Structural and Serologic Modifications in Blood Group Antigens by Homology Modeling.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 451-451
Author(s):  
Connie M. Westhoff ◽  
Dwane E. Wylie
Keyword(s):  
Crystal Structure ◽  
Amino Acid ◽  
Homology Modeling ◽  
Blood Group ◽  
Amino Acid Change ◽  
Single Amino Acid ◽  
Side Chain ◽  
Blood Group Antigens ◽  
Aromatic Side Chain ◽  
Transport Channel

Abstract Homology modeling of blood group proteins offers the possibility of predicting the effect of amino acid changes on serologic phenotype and immunogenicity. The location of an amino acid change within known structural motifs, its phylogenetic conservation, and its proximity to known epitopes give insight into its potential effect on protein structure and, consequently, its clinical significance. We applied this approach to investigate the loss of membrane expression of the Dombrock blood group antigens in a patient with a single amino acid change and to investigate RhD alterations in weak D phenotypes. The Dombrock homology model was derived with rat ART2.2 crystal structure as template. For the RhD model, the crystal structure of the Rh-like-ammonia transporter from Nitrosomonas europaea was used. Protein alignment was derived with Clustal X, adjusted visually, and submitted to the Swiss Modeling server. Models were viewed with Deep View Swiss Pdb Viewer. The Dombrock null containes a Phe62Ser substitution. This Phe (F) residue is located in an FDDQY motif near the COOH terminus. This region of the protein also contains a HYYLT motif. These two motifs are highly conserved in the ART protein family and contribute several aromatic amino acids to this region of the molecule. Aromatic side chain interactions between these residues could contribute to the stability of the Do protein. In support, the distance in the ART2.2 crystal structure between Phe in FDDQY and His in HYYLT is 3.7 Å, which is the appropriate distance for aromatic side chain interactions. This is also the measured distance between these two residues in the Do model. Thus, protein modeling indicates that the Phe62Ser mutation disrupts important stacking interactions between Phe62 and His160. When amino acid changes causing weak D phenotypes were examined, some of those affecting expression of RhD were located near the vestigial transport channel. These include the Trp220Arg mutation (weak D Type 16). This Trp residue is part of the transport channel in Nitrosomonas and is conserved in Rh proteins of almost all species. Its role in maintaining Rh structure is indicated by the dramatic effect its modification has on protein and epitope expression. Additionally, Arg114Trp change (weak D Type 17), which is also near the channel, reduces D expression to only 66 antigen sites/cell. GlyXXXGly motifs stabilize interactions of adjacent alpha helices in membrane proteins. Evidence for a role in stabilization of RhD is revealed by the Gly282Asp mutation (weak D Type 15) which is part of such a motif. In addition, a D-epitope in loop 3 is near the 282Asp residue. Alteration of helical packing accompanied by epitope conformation could explain production of anti-D in patients with weak D Type 15. Homology modeling is an important tool for understanding the structure and serologic bases of blood group proteins and will continue to give important insight as more protein crystal structures become available.

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