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Author: Tengfang Huang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
In addition to the twenty amino acids that are universally found as building blocks of proteins, nonprotein amino acids are also present in numerous plant species. One such nonprotein amino acid, meta -tyrosine, is abundant in the root exudates of Chewings fescue (Festuca rubra L. ssp. commutata ). Consistent with the phytotoxic effects of mtyrosine, prior studies showed that Chewings fescue has superior weed-suppressive capacity in field trials involving dozens of turf grass varieties. Further research with m-tyrosine demonstrates that this compound is stored in a different compartment than the protein amino acids, and can be easily washed off fescue roots with aqueous solutions. Chewings fescue roots have enzymatic activity, likely from a cytochrome P450, for synthesizing m-tyrosine from phenylalanine. An EST library was constructed from roots of Chewings fescue and four candidate cytochrome P450 genes are identified and cloned. When added to A. thaliana growth medium, m-tyrosine can be misincorporated into A. thaliana proteins. Several protein amino acids, in particular phenylalanine, partially rescue the toxicity of m-tyrosine. Correspondingly, a screen for m-tyrosine resistance in A. thaliana identified a mutant that over-accumulates free phenylalanine. Map-based cloning showed that the genetic basis of this phenotype is a dt2-1D, a mutant allele of ADT2, which encodes arogenate dehydratase, the final enzyme of the phenylalanine biosynthesis pathway. Characterization of ADT2 and its mutant form revealed feed-back regulation of phenylalanine biosynthesis, which depends on a critical motif of the ADT2 protein. Overexpression of the feedback-insensitive a dt2- 1D produces even higher levels of free phenylalanine and has pleiotropic physiological consequences, including abnormal leaf development, resistance to 5methyltryptophan, reduced growth of the generalist lepidopteran herbivore Trichoplusia ni (cabbage looper), and increased salt tolerance. Finally, several hypotheses for m-tyrosine modes of action were tested and discussed.
Author: Tengfang Huang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
In addition to the twenty amino acids that are universally found as building blocks of proteins, nonprotein amino acids are also present in numerous plant species. One such nonprotein amino acid, meta -tyrosine, is abundant in the root exudates of Chewings fescue (Festuca rubra L. ssp. commutata ). Consistent with the phytotoxic effects of mtyrosine, prior studies showed that Chewings fescue has superior weed-suppressive capacity in field trials involving dozens of turf grass varieties. Further research with m-tyrosine demonstrates that this compound is stored in a different compartment than the protein amino acids, and can be easily washed off fescue roots with aqueous solutions. Chewings fescue roots have enzymatic activity, likely from a cytochrome P450, for synthesizing m-tyrosine from phenylalanine. An EST library was constructed from roots of Chewings fescue and four candidate cytochrome P450 genes are identified and cloned. When added to A. thaliana growth medium, m-tyrosine can be misincorporated into A. thaliana proteins. Several protein amino acids, in particular phenylalanine, partially rescue the toxicity of m-tyrosine. Correspondingly, a screen for m-tyrosine resistance in A. thaliana identified a mutant that over-accumulates free phenylalanine. Map-based cloning showed that the genetic basis of this phenotype is a dt2-1D, a mutant allele of ADT2, which encodes arogenate dehydratase, the final enzyme of the phenylalanine biosynthesis pathway. Characterization of ADT2 and its mutant form revealed feed-back regulation of phenylalanine biosynthesis, which depends on a critical motif of the ADT2 protein. Overexpression of the feedback-insensitive a dt2- 1D produces even higher levels of free phenylalanine and has pleiotropic physiological consequences, including abnormal leaf development, resistance to 5methyltryptophan, reduced growth of the generalist lepidopteran herbivore Trichoplusia ni (cabbage looper), and increased salt tolerance. Finally, several hypotheses for m-tyrosine modes of action were tested and discussed.
Author: P. Gopalakrishnakone
Publisher:
ISBN: 9789400767287
Category : Plant toxins
Languages : en
Pages :
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Author: Gerald Rosenthal
Publisher: Elsevier
ISBN: 0323157742
Category : Science
Languages : en
Pages : 284
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Book Description
Plant Nonprotein Amino and Imino Acids: Biological, Biochemical, and Toxicological Properties provides a comprehensive discussion of plant nonprotein amino acids. Much of this monograph is written with the neophyte in mind, thus necessitating the presentation of certain basic concepts that are well-known to the advanced worker. Rather than providing an exhaustive coverage of the subject matter, the book attempts to represent effectively the state of the art; to provide a helpful means of identifying and locating the pertinent literature; and to present the basic information necessary to encourage other workers to enter into the study of the nonprotein amino acids. The book begins with a review of nomenclature and physicochemical properties. This is followed by a discussion of analytical methods such as partition paper chromatography, thin-layer chromatography, ninhydrin color reaction, ion-exchange chromatography, and gas chromatography. Subsequent chapters deal with the toxicity of some nonprotein amino acids and their ability to exert debilitating effects in a host of organisms; and the intermediary metabolism of nonprotein amino acids.
Author: Nathaniel Shimon Howitz
Publisher:
ISBN:
Category :
Languages : en
Pages : 139
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Book Description
Faithful translation of the genetic code into amino acid sequences is important for the viability of organisms. One source of error in translation is the mischarging of tRNAs with the incorrect amino acid due to structural similarities between the cognate and non-cognate amino acids. If gone unchecked, these mischarged tRNAs would provide an amino acid to the ribosome that does not match its codon, thereby causing mistranslation of the mRNA sequence. The proteins that are responsible for charging tRNAs with the correct amino acids are called aminoacyl-tRNA synthetases (aaRS). Some of these aaRSs have evolved an editing mechanism that allows them to cleave off a non-cognate amino acid from the mischarged tRNA, which is broadly conserved across all domains of life. This editing activity seems like it would be essential for life, however there are many examples of organisms who have lost their editing function to no ill effect. Moreover, there are examples of organisms that have conserved their editing function, but do not show a growth defect when it is eliminated, such as E. coli and its phenylalanine aaRS (PheRS). We chose to study E. coli's PheRS to understand why its editing function is evolutionarily conserved. We discovered that the non-protein amino acid meta-Tyrosine (m-Tyr) is toxic to PheRS editing-defective (PheRS edit-) E. coli. We then sought to understand why m-Tyr is so toxic to PheRS edit- cells. We used chemical mutagenesis to find m-Tyr resistant mutants and then performed whole genome sequencing to find mutated genes that could contribute to the resistance. We found that mutations in uptake and efflux transport could provide resistance by keeping or getting m-Tyr out of the cell. We also identified a resistance mutation that likely elevated Phe production, which provided resistance by most likely increasing competitive inhibition of the m-Tyr. We also observed PheRS edit- E. coli after m-Tyr exposure directly via light and electron microscopy. We observed large protein aggregates forming in the cells, which indicated that the m-Tyr destabilized a large fraction of the proteome. We also performed transcriptomic analysis of PheRS edit- E. coli after m-Tyr exposure to see what stress responses they used to deal with m-Tyr toxicity. We found a strong induction of the unfolded protein stress response, as well as oxidative stress, DNA damage stress, and indications of lost ion homeostasis. Based on these findings, we proposed a model of m-Tyr toxicity that involves a cascading and self-reinforcing chain reaction of cellular stresses that ultimately leads to cell death.
Author: Institute of Medicine
Publisher: National Academies Press
ISBN: 0309063469
Category : Technology & Engineering
Languages : en
Pages : 448
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Book Description
It is a commonly held belief that athletes, particularly body builders, have greater requirements for dietary protein than sedentary individuals. However, the evidence in support of this contention is controversial. This book is the latest in a series of publications designed to inform both civilian and military scientists and personnel about issues related to nutrition and military service. Among the many other stressors they experience, soldiers face unique nutritional demands during combat. Of particular concern is the role that dietary protein might play in controlling muscle mass and strength, response to injury and infection, and cognitive performance. The first part of the book contains the committee's summary of the workshop, responses to the Army's questions, conclusions, and recommendations. The remainder of the book contains papers contributed by speakers at the workshop on such topics as, the effects of aging and hormones on regulation of muscle mass and function, alterations in protein metabolism due to the stress of injury or infection, the role of individual amino acids, the components of proteins, as neurotransmitters, hormones, and modulators of various physiological processes, and the efficacy and safety considerations associated with dietary supplements aimed at enhancing performance.
Author: Nina Filip
Publisher: BoD – Books on Demand
ISBN: 1789847281
Category : Science
Languages : en
Pages : 74
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Book Description
The first description of homocysteine (Hcy), a non-proteinogenic amino acid, was introduced in a case study more than 70 years ago. In recent years, numerous studies have shown a positive correlation between serum levels and various diseases, especially vascular pathology. Vitamins B6, B12, and folic acid play a major role in controlling homocysteine levels. In this book are presented both methods for the determination of homocysteine and its involvement in human pathology. Homocysteine levels can be taken as an early indicator for the detection of cardiovascular diseases because Hcy levels increase after a myocardial infarction or stroke.
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309040418
Category : Medical
Languages : en
Pages : 298
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Book Description
Since its introduction in 1943 Recommended Dietary Allowances has become the accepted source of nutrient allowances for healthy people. These Recommended Dietary Allowances (RDAs) are used throughout the food and health fields. Additionally, RDAs serve as the basis for the U.S. Recommended Daily Allowances, the Food and Drug Administration's standards for nutrition labeling of foods. The 10th Edition includes research results and expert interpretations from years of progress in nutrition research since the previous edition and provides not only RDAs but also "Estimated Safe and Adequate Daily Dietary Intakes"â€"provisional values for nutrients where data were insufficient to set an RDA. Organized by nutrient for ready reference, the volume reviews the function of each nutrient in the human body, sources of supply, effects of deficiencies and excessive intakes, relevant study results, and more. The volume concludes with the invaluable "Summary Table of Recommended Dietary Allowances," a convenient and practical summary of the recommendations.
Author: Gita Cherian
Publisher:
ISBN:
Category : Biology
Languages : en
Pages :
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Author: Michel Fleck
Publisher: Springer
ISBN: 3319062999
Category : Medical
Languages : en
Pages : 581
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Book Description
Over the last decades, amino acids have been found to be of importance in many fields of science. Apart from their biological function, this family of organic compounds has been employed in the synthesis of a vast variety of salts, with impact on areas such as materials science, pharmaceutical or physical research. This covers a wide range, from the discovery of important ferroelectrics or non-linear optical materials to nutrients, flavor enhancers or drugs. This book describes amino acids and their salts with cations, anions and inorganic compounds from a chemical, physical and crystallographical point of view. Additional data on structural properties, crystal growth and the relation of structure and physical properties of amino acid salts is discussed.
Author:
Publisher:
ISBN: 9780815332183
Category : Cells
Languages : en
Pages : 0
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