scholarly journals Nicotinamide riboside–amino acid conjugates that are stable to purine nucleoside phosphorylase

2020 ◽  
Vol 18 (15) ◽  
pp. 2877-2885
Author(s):  
Faisal Hayat ◽  
Marie E. Migaud
Keyword(s):  
Amino Acid ◽  
Acid Ester ◽  
Purine Nucleoside Phosphorylase ◽  
Amino Acid Ester ◽  
Purine Nucleoside ◽  
Nucleoside Phosphorylase ◽  
Amino Acid Conjugates ◽  
Nicotinamide Riboside

O5′ amino acid ester conjugates of nicotinamide riboside, generated via a reduced intermediate, are stable to purine nucleoside phosphorylase.

scholarly journals Structure of grouper iridovirus purine nucleoside phosphorylase

2010 ◽  
Vol 66 (2) ◽  
pp. 155-162
Author(s):  
You-Na Kang ◽  
Yang Zhang ◽  
Paula W. Allan ◽  
William B. Parker ◽  
Jing-Wen Ting ◽  
...  
Keyword(s):  
Amino Acid ◽  
Active Site ◽  
Binding Sites ◽  
Purine Nucleoside Phosphorylase ◽  
Purine Nucleoside ◽  
Phosphate Binding ◽  
Nucleoside Phosphorylase ◽  
Cell Parameters ◽  
Phosphate Ion ◽  
Enzymatic Activity Assay

Purine nucleoside phosphorylase (PNP) catalyzes the reversible phosphorolysis of purine ribonucleosides to the corresponding free bases and ribose 1-phosphate. The crystal structure of grouper iridovirus PNP (givPNP), corresponding to the first PNP gene to be found in a virus, was determined at 2.4 Å resolution. The crystals belonged to space groupR3, with unit-cell parametersa= 193.0,c= 105.6 Å, and contained four protomers per asymmetric unit. The overall structure of givPNP shows high similarity to mammalian PNPs, having an α/β structure with a nine-stranded mixed β-barrel flanked by a total of nine α-helices. The predicted phosphate-binding and ribose-binding sites are occupied by a phosphate ion and a Tris molecule, respectively. The geometrical arrangement and hydrogen-bonding patterns of the phosphate-binding site are similar to those found in the human and bovine PNP structures. The enzymatic activity assay of givPNP on various substrates revealed that givPNP can only accept 6-oxopurine nucleosides as substrates, which is also suggested by its amino-acid composition and active-site architecture. All these results suggest that givPNP is a homologue of mammalian PNPs in terms of amino-acid sequence, molecular mass, substrate specificity and overall structure, as well as in the composition of the active site.

scholarly journals Isotope-specific and amino acid-specific heavy atom substitutions alter barrier crossing in human purine nucleoside phosphorylase

2015 ◽  
Vol 112 (36) ◽  
pp. 11247-11251 ◽  
Author(s):  
Javier Suarez ◽  
Vern L. Schramm
Keyword(s):  
Amino Acid ◽  
Transition State ◽  
State Formation ◽  
Purine Nucleoside Phosphorylase ◽  
Mass Difference ◽  
Heavy Atom ◽  
Catalytic Site ◽  
Purine Nucleoside ◽  
Barrier Crossing ◽  
Nucleoside Phosphorylase

Computational chemistry predicts that atomic motions on the femtosecond timescale are coupled to transition-state formation (barrier-crossing) in human purine nucleoside phosphorylase (PNP). The prediction is experimentally supported by slowed catalytic site chemistry in isotopically labeled PNP (13C, 15N, and 2H). However, other explanations are possible, including altered volume or bond polarization from carbon-deuterium bonds or propagation of the femtosecond bond motions into slower (nanoseconds to milliseconds) motions of the larger protein architecture to alter catalytic site chemistry. We address these possibilities by analysis of chemistry rates in isotope-specific labeled PNPs. Catalytic site chemistry was slowed for both [2H]PNP and [13C, 15N]PNP in proportion to their altered protein masses. Secondary effects emanating from carbon–deuterium bond properties can therefore be eliminated. Heavy-enzyme mass effects were probed for local or global contributions to catalytic site chemistry by generating [15N, 2H]His8-PNP. Of the eight His per subunit, three participate in contacts to the bound reactants and five are remote from the catalytic sites. [15N, 2H]His8-PNP had reduced catalytic site chemistry larger than proportional to the enzymatic mass difference. Altered barrier crossing when only His are heavy supports local catalytic site femtosecond perturbations coupled to transition-state formation. Isotope-specific and amino acid specific labels extend the use of heavy enzyme methods to distinguish global from local isotope effects.

Eco-Friendly Synthesis of Peptides Using Fmoc-Amino Acid Chlorides as Coupling Agent Under Biphasic Condition

2020 ◽  
Vol 27 ◽  
Author(s):  
Santosh Y. Khatavi ◽  
K. Kantharaju
Keyword(s):  
Amino Acid ◽  
Acid Chloride ◽  
Acid Ester ◽  
Analytical Techniques ◽  
Peptide Bond ◽  
Amino Acid Ester ◽  
Acid Chlorides ◽  
Peptide Bond Formation ◽  
Green Protocol ◽  
Additional Base

Background: Agro-waste derived solvent media act as a greener process for the peptide bond formation using Nα - Fmoc-amino acid chloride and amino acid ester salt with in situ neutralization and coupling under biphasic condition. The Fmoc-amino acid chlorides are prepared by the reported procedure of freshly distilled SOCl2 with dry CH2Cl2. The protocol found many added advantages such as neutralization of amino acid ester salt and not required additional base for the neutralization, and directly coupling take place with Fmoc-amino acid chloride gave final product dipeptide ester in good to excellent yields. The protocol occurs with complete stereo chemical integrity of the configuration of substrates. Here, we revisited Schotten-Baumann condition, instead of using inorganic base. Objective: To develop green protocol for the synthesis of peptide bond using Fmoc-amino acid chloride with amino acid esters salt. Methods: The final product isolated is analyzed in several spectroscopic and analytical techniques such as FT-IR, 1H-, 13CNMR, Mass spectrometry and RP-HPLC to check stereo integrity and purity of the product. Conclusion: The present method developed greener using natural agro-waste (lemon fruit shell ash) derived solvent medium for the reaction and not required chemical entity.

Purine nucleoside phosphorylase: Isolation and characterization

1990 ◽  
Vol 55 (12) ◽  
pp. 2987-2999 ◽  
Author(s):  
Katarina Šedivá ◽  
Ivan Votruba ◽  
Antonín Holý ◽  
Ivan Rosenberg
Keyword(s):  
Molecular Weight ◽  
Purine Nucleoside Phosphorylase ◽  
Purine Nucleoside ◽  
Leukemia Cells ◽  
Ph Optimum ◽  
Nucleoside Phosphorylase ◽  
Isolation And Characterization ◽  
Reaction Proceeds ◽  
The Matrix ◽  
Sepharose 4B

Purine nucleoside phosphorylase (PNP) from mouse leukemia cells L1210 was purified to homogeneity by a combination of ion exchange and affinity chromatography using AE-Sepharose 4B and 9-(p-succinylaminobenzyl)hypoxanthine as the matrix and the ligand, respectively. The native enzyme has a molecular weight of 104 000 and consists of three subunits of equal molecular weight of 34 000. The results of isoelectric focusing showed that the enzyme is considerably microheterogeneous over the pI-range 4.0-5.8 and most likely consists of eight isozymes. The temperature and pH-optimum of phosphorolysis, purine nucleoside synthesis and also of transribosylation is identical, namely 55 °C and pH 7.4. The transribosylation reaction proceeds in the presence of phosphate only. The following Km-values (μmol l-1) were determined for phosphorolysis: inosine 40, 2'-deoxyinosine 47, guanosine 27, 2'-deoxyguanosine 32. The Km-values (μmol l-1) of purine riboside and deoxyriboside synthesis are lower than the values for phosphorolysis (hypoxanthine 18 and 34, resp., guanine 8 and 11, resp.). An affinity lower by one order shows PNP for (-D-ribose-1-phosphate, (-D-2-deoxyribose-1-phosphate (Km = 200 μmol l-1 in both cases) and phosphate (Km = 805 μmol l-1). The substrate specificity of the enzyme was also studied: positions N(1), C(2) and C(8) are decisive for the binding of the substrate (purine nucleoside).

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