ChemInform Abstract: Synthesis and Structure Determination of Some Sugar Amino Acids Related to Alanine and 6-Deoxymannojirimycin.

Wuyi rock tea (WRT), a type of oolong tea, is famous for ‘rock flavor’ with characteristic taste and aroma. The qualitative and quantitative changes of the nonvolatile constituents and taste profiles were investigated during the WRT production process by analyzing of polyphenols, caffeine, amino acids, L-theanine and total sugar, coupled with sensory evaluation and determination of dose-over-threshold values. The contents of L-theanine, total sugar, amino acids and some catechins varied considerably except for GA, GCG and GC that increased significantly during the process, while the amount of caffeine was relatively stable. Astringent, bitter, sweet and umami taste properties were predicted. In accordance with the sensory evaluation, there was no umami-like taste in the finished tea that underwent full fire processing, which is essential for WRT to enhance the mellow, heavy taste, and weaken the bitter taste. EGCG and caffeine contributed the most to the astringent, bitter taste of WRT. This study provides a comprehensive profile of the changes in taste characteristics during the WRT manufacturing process.

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Fluorescence Reagents for Labelling of Biomolecules. Part II. Reactions of 9-Isothiocyanatoacridine with Amino Acids

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19940213 ◽

1994 ◽

Vol 59 (1) ◽

pp. 213-221 ◽

Cited By ~ 13

Author(s):

Dušan Podhradský ◽

Peter Oravec ◽

Marián Antalík ◽

Pavol Kristian

Keyword(s):

Amino Acids ◽

Amino Acid ◽

Structure Determination ◽

Phenyl Isothiocyanate ◽

Amino Acid Derivatives ◽

Analogous Reaction ◽

Kinetic Measurements ◽

Fluorescence Labelling

N-(9-Acridinylthiocarbamoyl)amino acids (ATC-AA) II - VII were synthesized by reaction of amino acids with 9-isothiocyanatoacridine I, a new fluorescence labelling agent. The amino acid derivatives II - VII show high relative fluorescence, which is suitable for the determination of nanomolar amounts of ATC-AA. The kinetic measurements show that reaction of I with amino acids is 6 to 22 times faster than analogous reaction of phenyl isothiocyanate. The possibility of using 9-isothiocyanatoacridine for structure determination of proteins is discussed.

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Lithium coordination to amino acids and peptides. Synthesis, spectroscopic characterization and structure determination of lithium complexes of neutral and anionic glycine and diglycine

Inorganica Chimica Acta ◽

10.1016/0020-1693(93)03786-a ◽

1994 ◽

Vol 218 (1-2) ◽

pp. 121-131 ◽

Cited By ~ 24

Author(s):

Gerhard Müller ◽

Gerd-Michael Maier ◽

Martin Lutz

Keyword(s):

Amino Acids ◽

Structure Determination ◽

Spectroscopic Characterization ◽

Peptides Synthesis ◽

Lithium Complexes

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Insights into the Cnx1E catalyzed MPT-AMP hydrolysis

Bioscience Reports ◽

10.1042/bsr20191806 ◽

2020 ◽

Vol 40 (1) ◽

Cited By ~ 6

Author(s):

Thomas W. Hercher ◽

Joern Krausze ◽

Sven Hoffmeister ◽

Dagmar Zwerschke ◽

Thomas Lindel ◽

...

Keyword(s):

Amino Acids ◽

Arabidopsis Thaliana ◽

Structure Determination ◽

Active Site ◽

Molybdenum Cofactor ◽

Water Complex ◽

Potential Reason ◽

Aspartate Residue ◽

Hydrolysis Activity

Abstract Molybdenum insertases (Mo-insertases) catalyze the final step of molybdenum cofactor (Moco) biosynthesis, an evolutionary old and highly conserved multi-step pathway. In the first step of the pathway, GTP serves as substrate for the formation of cyclic pyranopterin monophosphate, which is subsequently converted into molybdopterin (MPT) in the second pathway step. In the following synthesis steps, MPT is adenylated yielding MPT-AMP that is subsequently used as substrate for enzyme catalyzed molybdate insertion. Molybdate insertion and MPT-AMP hydrolysis are catalyzed by the Mo-insertase E-domain. Earlier work reported a highly conserved aspartate residue to be essential for Mo-insertase functionality. In this work, we confirmed the mechanistic relevance of this residue for the Arabidopsis thaliana Mo-insertase Cnx1E. We found that the conservative substitution of Cnx1E residue Asp274 by Glu (D274E) leads to an arrest of MPT-AMP hydrolysis and hence to the accumulation of MPT-AMP. We further showed that the MPT-AMP accumulation goes in hand with the accumulation of molybdate. By crystallization and structure determination of the Cnx1E variant D274E, we identified the potential reason for the missing hydrolysis activity in the disorder of the region spanning amino acids 269 to 274. We reasoned that this is caused by the inability of a glutamate in position 274 to coordinate the octahedral Mg2+-water complex in the Cnx1E active site.

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