ChemInform Abstract: THE SYSTEM 2-HALOETHYL ESTER/CHOLINE ESTER AS A TWO-STEP PROTECTIVE GROUP OF THE CARBOXYL FUNCTIONAL GROUP OF AMINO ACIDS AND PEPTIDES

1979 ◽  
Vol 10 (35) ◽  
Author(s):  
H. KUNZ ◽  
M. BUCHHOLZ
2013 ◽  
Vol 405 ◽  
pp. 121-127 ◽  
Author(s):  
Jaromír Vinklárek ◽  
Jan Honzíček ◽  
Milan Erben ◽  
Iva Klepalová ◽  
Aleš Eisner ◽  
...  

Author(s):  
Md. Mahbubur Rahman ◽  
Dongtao Liu ◽  
Nasrin Siraj Lopa ◽  
Jong-Beom Baek ◽  
Chang-Hoon Nam ◽  
...  

2013 ◽  
Vol 44 (2s) ◽  
Author(s):  
Elisabetta Stella ◽  
Roberto Moscetti ◽  
Letizia Carletti ◽  
Giuseppina Menghini ◽  
Francesco Fabrizi ◽  
...  

The study demonstrated the feasibility of the near infrared (NIR) spectroscopy use for hazelnut-cultivar sorting. Hazelnut spectra were acquired from 600 fruit for each cultivar sample, two diffuse reflectance spectra were acquired from opposite sides of the same hazelnut. Spectral data were transformed into absorbance before the computations. A different variety of spectral pretreatments were applied to extract characteristics for the classification. An iterative Linear Discriminant Analysis (LDA) algorithm was used to select a relatively small set of variables to correctly classify samples. The optimal group of features selected for each test was analyzed using Partial Least Squares Discriminant Analysis (PLS-DA). The spectral region most frequently chosen was the 1980-2060 nm range, which corresponds to best differentiation performance for a total minimum error rate lower than 1.00%. This wavelength range is generally associated with stretching and bending of the N-H functional group of amino acids and proteins. The feasibility of using NIR Spectroscopy to distinguish different hazelnut cultivars was demonstrated.


1981 ◽  
Vol 77 (1) ◽  
pp. 23-39 ◽  
Author(s):  
I Shimada ◽  
T Tanimura

N-Formylation and N-methylation of the alpha-amino group of L-phenylalanine result in extremely decreased responses of the labellar sugar receptor of the fleshfly, whereas the same structural alteration of L-valine hardly affects the response. Methyl esterification of the alpha-carboxyl group of phenylalanine, on the other hand, maintains the response to some extent, but similar treatment of valine completely diminishes the response. The aromatic structure in phenylalanine is not essential for stimulation. These results suggest a substantial difference in the stereospecificities and functional group specificities of the furnase (F) and aliphatic carboxylate (T) sites in the sugar receptor. The effect of small peptides on the sugar receptor was examined systematically. Their effectiveness depends mainly on the place of the constituent amino acids rather than on their composition, indicating the decisive role that certain aliphatic amino acids in the C-terminal position play in stimulation. Remarkable regularities in the stimulating effectiveness of small peptides exactly correspond to the stereospecificity of each receptor site. We propose two hypothetical models of the F and T sites, which involve three and two subsites, respectively, that are capable of hydrogen bond formation. The F and T sites also have a hydrophobic subsite that discriminates the R groups of the stimulants and a few spatial barriers.


Molecules ◽  
2019 ◽  
Vol 24 (5) ◽  
pp. 866 ◽  
Author(s):  
Janusz Petkowski ◽  
William Bains ◽  
Sara Seager

Phosphorous-containing molecules are essential constituents of all living cells. While the phosphate functional group is very common in small molecule natural products, nucleic acids, and as chemical modification in protein and peptides, phosphorous can form P–N (phosphoramidate), P–S (phosphorothioate), and P–C (e.g., phosphonate and phosphinate) linkages. While rare, these moieties play critical roles in many processes and in all forms of life. In this review we thoroughly categorize P–N, P–S, and P–C natural organophosphorus compounds. Information on biological source, biological activity, and biosynthesis is included, if known. This review also summarizes the role of phosphorylation on unusual amino acids in proteins (N- and S-phosphorylation) and reviews the natural phosphorothioate (P–S) and phosphoramidate (P–N) modifications of DNA and nucleotides with an emphasis on their role in the metabolism of the cell. We challenge the commonly held notion that nonphosphate organophosphorus functional groups are an oddity of biochemistry, with no central role in the metabolism of the cell. We postulate that the extent of utilization of some phosphorus groups by life, especially those containing P–N bonds, is likely severely underestimated and has been largely overlooked, mainly due to the technological limitations in their detection and analysis.


2020 ◽  
Vol 26 (54) ◽  
pp. 12338-12342
Author(s):  
Ivana Drienovská ◽  
Matúš Gajdoš ◽  
Alexia Kindler ◽  
Mahsa Takhtehchian ◽  
Barbara Darnhofer ◽  
...  

2017 ◽  
Vol 15 (34) ◽  
pp. 7157-7164 ◽  
Author(s):  
Huanhuan Liu ◽  
Feiyu Zhou ◽  
Wen Luo ◽  
Yuxin Chen ◽  
Chenyang Zhang ◽  
...  

A practical and concise protocol for the efficient synthesis of pyrrolo[1,2-a]quinoxalines from readily available α-amino acids and 2-(1H-pyrrol-1-yl)anilines under transition metal-free conditions has been established. This protocol, which includes the formation of new C–C and C–N bonds, features a wide substrate scope with a broad range of functional group tolerance.


2021 ◽  
Vol 12 ◽  
Author(s):  
Jian Yao ◽  
Yan Zeng ◽  
Miaoxiao Wang ◽  
Yue-Qin Tang

In natural communities, microbes exchange a variety of metabolites (public goods) with each other, which drives the evolution of auxotroph and shapes interdependent patterns at community-level. However, factors that determine the strategy of public goods synthesis for a given community member still remains to be elucidated. In anaerobic methanogenic communities, energy availability of different community members is largely varied. We hypothesized that this uneven energy availability contributed to the heterogeneity of public goods synthesis ability among the members in these communities. We tested this hypothesis by analyzing the synthetic strategy of amino acids of the bacterial and archaeal members involved in four previously enriched anaerobic methanogenic communities residing in thermophilic chemostats. Our analyses indicate that most of the members in the communities did not possess ability to synthesize all the essential amino acids, suggesting they exchanged these essential public goods to establish interdependent patterns for survival. Importantly, we found that the amino acid synthesis ability of a functional group was largely determined by how much energy it could obtain from its metabolism in the given environmental condition. Moreover, members within a functional group also possessed different amino acid synthesis abilities, which are related to their features of energy metabolism. Our study reveals that energy availability is a key driver of microbial evolution in presence of metabolic specialization at community level and suggests the feasibility of managing anaerobic methanogenic communities for better performance through controlling the metabolic interactions involved.


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