AMINO ACID RESIDUE ILE211 IS ESSENTIAL FOR THE ENZYMATIC ACTIVITY OF HUMAN UDP-GLUCURONOSYLTRANSFERASE 1A10 (UGT1A10)

2004 ◽  
Vol 32 (4) ◽  
pp. 455-459 ◽  
Author(s):  
Isabelle Martineau ◽  
André Tchernof ◽  
Alain Bélanger
Keyword(s):  
Amino Acid ◽  
Enzymatic Activity ◽  
Amino Acid Residue ◽  
Udp Glucuronosyltransferase

scholarly journals A critical amino acid residue, Asp446, in UDP-glucuronosyltransferase

1997 ◽  
Vol 325 (3) ◽  
pp. 587-591 ◽  
Author(s):  
Hidetomo IWANO ◽  
Hiroshi YOKOTA ◽  
Satoru OHGIYA ◽  
Naomi YOTUMOTO ◽  
Akira YUASA
Keyword(s):  
Amino Acid ◽  
Amino Acid Residue ◽  
Amino Acid Substitution ◽  
Critical Role ◽  
Enzymic Activity ◽  
Male Rat ◽  
Transferase Activity ◽  
Rt Pcr ◽  
Taq Polymerase ◽  
Udp Glucuronosyltransferase

An amino acid residue, Asp446, was found to be essential for the enzymic activity of UDP-glucuronosyltransferase (UGT). We obtained a rat phenol UGT (UGT1*06) cDNA (named Ysh) from male rat liver by reverse-transcription (RT)-PCR using pfu polymerase. A mutant Ysh having two different bases, A1337G and G1384A (named Ysh A1337GC1384A), that result in two amino acid substitutions, D446G and V462M, was obtained by RT-PCR using Taq polymerase. Ysh was expressed functionally in microsomes of Saccharomyces cerevisiae strain AH22. However, the expressed protein from Ysh A1337GG1384A had no transferase activity. Two other mutant cDNAs with Ysh A1337G having one changed base, A1337G, resulting in one amino acid substitution, D446G, and Ysh G1384A having a changed base, G1384A, resulting in an amino acid substitution, V462M, were constructed and expressed in the yeast. The expressed protein from Ysh G1384A (named Ysh V462M) exhibited enzymic activity, but the one from Ysh A1337G (named Ysh D446G) did not show any activity at all. Asp446 was conserved in all UGTs and UDP-galactose:ceramide galactosyltransferases reported, suggesting that Asp446 plays a critical role in each enzyme.

Zur Strahleninaktivierung von Ribonuclease

1968 ◽  
Vol 23 (7) ◽  
pp. 934-943 ◽  
Author(s):  
Horst Jung ◽  
Helga Schüssler
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Low Temperature ◽  
Gamma Radiation ◽  
Enzymatic Activity ◽  
Amino Acid Residue ◽  
Atomic Hydrogen ◽  
Active Components ◽  
Experimental Conditions ◽  
Elution Pattern

Dry ribonuclease was irradiated with 60Co gamma radiation in vacuo, under oxygen atmosphere, and at 77 °K. By chromatography on Sephadex G-50 active ribonuclease was separated from inactive radiation products. From the elution pattern and by ultracentrifugation it was shown that mainly unfolded dimers are formed by gamma irradiation of dry ribonuclease. Amino acid analysis of these various products shows that in all components cystine, methionine, tyrosine, phenylalanine, lysine, and histidine are destroyed with increasing dose whereas glycine shows a small increase. Thus, in ribonuclease irradiated in the dry state the same amino acids are changed as was found after irradiation in aqueous solutions. The radiosensitivity of dry ribonuclease shows an increase by the presence of oxygen of about 2 and a decrease at low temperature in vacuo of about 5. The same factors were also found for the alteration of amino acids, which means that under various experimental conditions amino acid destruction is proportional to loss of enzymatic activity of ribonuclease. The observed selectivity of amino acid destruction may be explained by energy migration or by the attack of atomic hydrogen liberated at random from the molecule. The total number of amino acids destroyed per ribonuclease molecule increases with dose. In enzymatically inactive products this value is always higher by one amino acid residue than in the active components. From this result and from the increase with dose it is concluded that after destruction of one amino acid residue the ribonuclease molecule has a probability (not depending on dose of irradiation) of 0.45 to become inactivated whereas in 55 per cent of all cases the molecule maintains its enzymatic activity.

scholarly journals Aminopeptidases trim Xaa-Pro proteins, initiating their degradation by the Pro/N-degron pathway

2021 ◽  
Vol 118 (43) ◽  
pp. e2115430118
Author(s):  
Shun-Jia Chen ◽  
Leehyeon Kim ◽  
Hyun Kyu Song ◽  
Alexander Varshavsky
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Enzymatic Activity ◽  
Amino Acid Residue ◽  
Ubiquitin Ligase ◽  
Proteolytic System ◽  
A Subunit

N-degron pathways are proteolytic systems that recognize proteins bearing N-terminal (Nt) degradation signals (degrons) called N-degrons. Our previous work identified Gid4 as a recognition component (N-recognin) of the Saccharomyces cerevisiae proteolytic system termed the proline (Pro)/N-degron pathway. Gid4 is a subunit of the oligomeric glucose-induced degradation (GID) ubiquitin ligase. Gid4 targets proteins through the binding to their Nt-Pro residue. Gid4 is also required for degradation of Nt-Xaa-Pro (Xaa is any amino acid residue) proteins such as Nt-[Ala-Pro]-Aro10 and Nt-[Ser-Pro]-Pck1, with Pro at position 2. Here, we show that specific aminopeptidases function as components of the Pro/N-degron pathway by removing Nt-Ala or Nt-Ser and yielding Nt-Pro, which can be recognized by Gid4-GID. Nt-Ala is removed by the previously uncharacterized aminopeptidase Fra1. The enzymatic activity of Fra1 is shown to be essential for the GID-dependent degradation of Nt-[Ala-Pro]-Aro10. Fra1 can also trim Nt-[Ala-Pro-Pro-Pro] (stopping immediately before the last Pro) and thereby can target for degradation a protein bearing this Nt sequence. Nt-Ser is removed largely by the mitochondrial/cytosolic/nuclear aminopeptidase Icp55. These advances are relevant to eukaryotes from fungi to animals and plants, as Fra1, Icp55, and the GID ubiquitin ligase are conserved in evolution. In addition to discovering the mechanism of targeting of Xaa-Pro proteins, these insights have also expanded the diversity of substrates of the Pro/N-degron pathway.

scholarly journals Site-directed mutagenesis identified the key active site residues of alcohol acyltransferase PpAAT1 responsible for aroma biosynthesis in peach fruits

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Zhi-Zhong Song ◽  
Bin Peng ◽  
Zi-Xia Gu ◽  
Mei-Ling Tang ◽  
Bei Li ◽  
...  
Keyword(s):  
Amino Acid ◽  
Enzymatic Activity ◽  
Amino Acid Residue ◽  
Active Site ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Amino Acid Residues ◽  
Active Site Residues ◽  
Peach Fruit ◽  
Alcohol Acyltransferase

AbstractThe aroma of peach fruit is predominantly determined by the accumulation of γ-decalactone and ester compounds. A previous study showed that the biosynthesis of these aroma compounds in peach fruit is catalyzed by PpAAT1, an alcohol acyltransferase. In this work, we investigated the key active site residues responsible for γ-decalactone and ester biosynthesis. A total of 14 candidate amino acid residues possibly involved in internal esterification and 9 candidate amino acid residues possibly involved in esterification of PpAAT1 were assessed via site-directed mutagenesis. Analyses of the in vitro enzyme activities of PpAAT1 and its site-directed mutant proteins (PpAAT1-SMs) with different amino acid residue mutations as well as the contents of γ-decalactone in transgenic tobacco leaves and peach fruits transiently expressing PpAAT1 and PpAAT1-SMs revealed that site-directed mutation of H165 in the conserved HxxxD motif led to lost enzymatic activity of PpAAT1 in both internal esterification and its reactions, whereas mutation of the key amino acid residue D376 led to the total loss of γ-decalactone biosynthesis activity of PpAAT1. Mutations of 9 and 7 other amino acid residues also dramatically affected the enzymatic activity of PpAAT1 in the internal esterification and esterification reactions, respectively. Our findings provide a biochemical foundation for the mechanical biosynthesis of γ-decalactone and ester compounds catalyzed by PpAAT1 in peach fruits, which could be used to guide the molecular breeding of new peach species with more favorable aromas for consumers.

scholarly journals Kinetic characterization of yeast alcohol dehydrogenases. Amino acid residue 294 and substrate specificity.

1987 ◽  
Vol 262 (8) ◽  
pp. 3754-3761
Author(s):  
A.J. Ganzhorn ◽  
D.W. Green ◽  
A.D. Hershey ◽  
R.M. Gould ◽  
B.V. Plapp
Keyword(s):  
Amino Acid ◽  
Substrate Specificity ◽  
Amino Acid Residue ◽  
Kinetic Characterization ◽  
Alcohol Dehydrogenases

scholarly journals Amino Acid Residue at the 165th Position Tunes Eyfp Chromophore Maturation. A Structure-Based Design

2021 ◽  
Author(s):  
Nadya V. Pletneva ◽  
Eugene G. Maksimov ◽  
Elena A. Protasova ◽  
Anastasia V. Mamontova ◽  
Tatiana R. Simonyan ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Residue
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