ChemInform Abstract: Aglycone Fragmentation Accompanies β-Glucosidase-Catalyzed Hydrolysis of Salicortin, a Naturally-Occurring Phenol Glycoside.

ChemInform ◽  
2010 ◽  
Vol 22 (25) ◽  
pp. no-no
Author(s):  
T. P. CLAUSEN ◽  
J. W. KELLER ◽  
P. B. REICHARDT
Keyword(s):  
Naturally Occurring ◽  
Hydrolysis Of ◽  
Phenol Glycoside

Variation in Quantity of Methanol Recovered from Raisins

1963 ◽  
Vol 46 (2) ◽  
pp. 341-343
Author(s):  
M Alice Brown ◽  
James R Woodward ◽  
Floyd DeEds
Keyword(s):  
Methyl Ester ◽  
Esterase Activity ◽  
Enzymic Hydrolysis ◽  
Methanol Content ◽  
Naturally Occurring ◽  
Pectin Esterase ◽  
Hydrolysis Of

Abstract The amount of naturally occurring methanol in fruit must be known so that the quantity left as fumigation residue can be determined. In a study of methanol content of raisins, which had given inconsistent results, the raisins were subjected to different conditions of treatment immediately prior to methanol determination. Conditions that favored pectin esterase activity gave higher values for methanol content than conditions known to inactivate enzymes. Evidence was also obtained that both chemical and enzymic hydrolysis of methyl ester groups of pectic materials occur during analysis.

scholarly journals Crocetin: A Systematic Review

2022 ◽  
Vol 12 ◽  
Author(s):  
Zi-Liang Guo ◽  
Mao-Xing Li ◽  
Xiao-Lin Li ◽  
Peng Wang ◽  
Wei-Gang Wang ◽  
...  
Keyword(s):  
Systematic Review ◽  
Medicinal Plants ◽  
Total Synthesis ◽  
Drug Safety ◽  
Ripe Fruit ◽  
Bioactive Metabolite ◽  
Naturally Occurring ◽  
Hydrolysis Of ◽  
Application Prospects ◽  
Memory Enhancing

Crocetin is an aglycone of crocin naturally occurring in saffron and produced in biological systems by hydrolysis of crocin as a bioactive metabolite. It is known to exist in several medicinal plants, the desiccative ripe fruit of the cape jasmine belonging to the Rubiaceae family, and stigmas of the saffron plant of the Iridaceae family. According to modern pharmacological investigations, crocetin possesses cardioprotective, hepatoprotective, neuroprotective, antidepressant, antiviral, anticancer, atherosclerotic, antidiabetic, and memory-enhancing properties. Although poor bioavailability hinders therapeutic applications, derivatization and formulation preparation technologies have broadened the application prospects for crocetin. To promote the research and development of crocetin, we summarized the distribution, preparation and production, total synthesis and derivatization technology, pharmacological activity, pharmacokinetics, drug safety, drug formulations, and preparation of crocetin.

scholarly journals Processing of RNA Containing 8-Oxo-7,8-Dihydroguanosine (8-oxoG) by the Exoribonuclease Xrn-1

2021 ◽  
Vol 8 ◽  
Author(s):  
Cheyenne N. Phillips ◽  
Shawn Schowe ◽  
Conner J. Langeberg ◽  
Namoos Siddique ◽  
Erich G. Chapman ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Conformational Changes ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
Spatial Constraints ◽  
Phase Synthesis ◽  
Naturally Occurring ◽  
Processive Enzyme ◽  
Moving Band ◽  
Hydrolysis Of

Understanding how oxidatively damaged RNA is handled intracellularly is of relevance due to the link between oxidized RNA and the progression/development of some diseases as well as aging. Among the ribonucleases responsible for the decay of modified (chemically or naturally) RNA is the exonuclease Xrn-1, a processive enzyme that catalyzes the hydrolysis of 5′-phosphorylated RNA in a 5′→3′ direction. We set out to explore the reactivity of this exonuclease towards oligonucleotides (ONs, 20-nt to 30-nt long) of RNA containing 8-oxo-7,8-dihydroguanosine (8-oxoG), obtained via solid-phase synthesis. The results show that Xrn-1 stalled at sites containing 8-oxoG, evidenced by the presence of a slower moving band (via electrophoretic analyses) than that observed for the canonical analogue. The observed fragment(s) were characterized via PAGE and MALDI-TOF to confirm that the oligonucleotide fragment(s) contained a 5′-phosphorylated 8-oxoG. Furthermore, the yields for this stalling varied from app. 5–30% with 8-oxoG located at different positions and in different sequences. To gain a better understanding of the decreased nuclease efficiency, we probed: 1) H-bonding and spatial constraints; 2) anti-syn conformational changes; 3) concentration of divalent cation; and 4) secondary structure. This was carried out by introducing methylated or brominated purines (m1G, m6,6A, or 8-BrG), probing varying [Mg2+], and using circular dichroism (CD) to explore the formation of structured RNA. It was determined that spatial constraints imposed by conformational changes around the glycosidic bond may be partially responsible for stalling, however, the results do not fully explain some of the observed higher stalling yields. We hypothesize that altered π-π stacking along with induced H-bonding interactions between 8-oxoG and residues within the binding site may also play a role in the decreased Xrn-1 efficiency. Overall, these observations suggest that other factors, yet to be discovered/established, are likely to contribute to the decay of oxidized RNA. In addition, Xrn-1 degraded RNA containing m1G, and stalled mildly at sites where it encountered m6,6A, or 8-BrG, which is of particular interest given that the former two are naturally occurring modifications.

scholarly journals Hydrolysis of a naturally occurring β-glucoside by a broad-specificity β-glucosidase from liver

1986 ◽  
Vol 237 (2) ◽  
pp. 469-476 ◽  
Author(s):  
K L LaMarco ◽  
R H Glew
Keyword(s):  
Guinea Pig ◽  
Competitive Inhibitor ◽  
Heat Denaturation ◽  
Pig Liver ◽  
Naturally Occurring ◽  
Aryl Glycosides ◽  
Beta Glucosidase ◽  
Hydrolysis Of ◽  
Guinea Pig Liver ◽  
Broad Specificity

We have isolated from guinea-pig liver a broad-specificity beta-glucosidase of unknown function that utilizes as its substrate non-physiological aryl glycosides (e.g. 4-methylumbelliferyl beta-D-glucopyranoside, p-nitrophenyl beta-D-glucopyranoside). The present paper documents that this enzyme can be inhibited by various naturally occurring glycosides, including L-picein, dhurrin and glucocheirolin. In addition, L-picein, which acts as a competitive inhibitor of the broad-specificity beta-glucosidase (Ki 0.65 mM), is also a substrate for this enzyme (Km 0.63 mM; Vmax. 277,000 units/mg). Heat-denaturation, kinetic competition studies, chromatographic properties and pH optima all argue strongly that the broad-specificity beta-glucosidase is responsible for the hydrolysis of both the non-physiological aryl glycosides and L-picein. This paper demonstrates that beta-glucosidase can catalyse the hydrolysis of a natural glycoside, and may provide a key to understanding the function of this enigmatic enzyme. A possible role in the metabolism of xenobiotic compounds is discussed.

Synthesis of Flavonoid Sulfates. II. The Use of Aryl Sulfatase in the Synthesis of Flavonol-3-sulfates

1988 ◽  
Vol 43 (9-10) ◽  
pp. 625-630 ◽  
Author(s):  
Denis Barron ◽  
Ragai K. Ibrahim
Keyword(s):  
Convenient Method ◽  
Enzyme Hydrolysis ◽  
Quantitative Yield ◽  
Sulfate Ester ◽  
Aryl Sulfatase ◽  
Naturally Occurring ◽  
Complete Resistance ◽  
Hydrolysis Of

Abstract The rates of aryl sulfatase hydrolysis of several 7-, 4′- and 3-sulfated flavonoids were compared and found to follow the order 7 or 4′ >>> 3. The complete resistance of the 3-sulfate ester to enzyme hydrolysis provided a unique and convenient method for the synthesis of a number of naturally occurring flavonol-3-sulfates from the corresponding higher sulfated analogs in quantitative yield.

Preparation of α-aminothioamides from aldehydes

1987 ◽  
Vol 65 (2) ◽  
pp. 282-289 ◽  
Author(s):  
Martino Paventi ◽  
John T. Edward
Keyword(s):  
Amino Acids ◽  
Naturally Occurring ◽  
Hydrolysis Of

The conversion of aldehydes into α-aminonitriles and thence into imidazolidin-4-thiones has been studied. Hydrolysis of the appropriate imidazolidin-4-thiones gave thioamides of nine naturally occurring α-amino acids. The possible pre-biotic significance of these compounds is discussed.

scholarly journals Comparative Biochemical and Computational Study of the Role of Naturally Occurring Mutations at Ambler Positions 104 and 170 in GES β-Lactamases

2010 ◽  
Vol 54 (11) ◽  
pp. 4864-4871 ◽  
Author(s):  
Stathis D. Kotsakis ◽  
Vivi Miriagou ◽  
Eva Tzelepi ◽  
Leonidas S. Tzouvelekis
Keyword(s):  
Boronic Acid ◽  
Computational Study ◽  
Dynamic Simulations ◽  
Site Specific ◽  
Catalytic Behavior ◽  
Naturally Occurring ◽  
Hydrolysis Rates ◽  
Hydrolysis Of ◽  
Precise Role

ABSTRACT In GES-type β-lactamases, positions 104 and 170 are occupied by Glu or Lys and by Gly, Asn, or Ser, respectively. Previous studies have indicated an important role of these amino acids in the interaction with β-lactams, although their precise role, especially that of residue 104, remains uncertain. In this study, we constructed GES-1 (Glu104, Gly170), GES-2 (Glu104, Asn170), GES-5 (Glu104, Ser170), GES-6 (Lys104, Ser170), GES-7 (Lys104, Gly170), and GES-13 (Lys104, Asn170) by site-specific mutagenesis and compared their hydrolytic properties. Isogenic comparisons of β-lactam resistance levels conferred by these GES variants were also performed. Data indicated the following patterns: (i) Lys104-containing enzymes exhibited enhanced hydrolysis of oxyimino-cephalosporins and reduced efficiency against imipenem in relation to enzymes possessing Glu104, (ii) Asn170-containing enzymes showed reduced hydrolysis rates of penicillins and older cephalosporins, (iii) Ser170 enabled GES to hydrolyze cefoxitin efficiently, and (iv) Asn170 and Ser170 increased the carbapenemase character of GES enzymes but reduced their activity against ceftazidime. Molecular dynamic simulations of GES apoenzyme models, as well as construction of GES structures complexed with cefoxitin and an achiral ceftazidime-like boronic acid, provided insights into the catalytic behavior of the studied mutants. There were indications that an increased stability of the hydrogen bonding network of Glu166-Lys73-Ser70 and an altered positioning of Trp105 correlated with the substrate spectra, especially with acylation of GES by imipenem. Furthermore, likely effects of Ser170 on GES interactions with cefoxitin and of Lys104 on interactions with oxyimino-cephalosporins were revealed. Overall, the data unveiled the importance of residues 104 and 170 in the function of GES enzymes.

scholarly journals THE OCCURRENCE AND DISTRIBUTION OF ATROPINESTERASE, AND THE SPECIFICITY OF TROPINESTERASES

1941 ◽  
Vol 25 (2) ◽  
pp. 197-205 ◽  
Author(s):  
David Glick ◽  
Susi Glaubach
Keyword(s):  
Guinea Pig ◽  
Egg White ◽  
Pig Liver ◽  
Naturally Occurring ◽  
Hydrolysis Of ◽  
Guinea Pig Liver

Atropinesterase was found to exist in approximately one out of every four rabbits, and no relation could be observed between the incidence of the enzyme and season, sex, color, age, or weight. The occurrence of the enzyme was also shown to be unrelated to that of cholinesterase. The distribution of atropinesterase in the blood and organs of rabbits was studied; the animals devoid of the enzyme in their blood contained no demonstrable activity in any of the organ extracts tested. The presence of atropinesterase in frog liver, and its absence from the serum, has been confirmed. Hydrolysis of homatropine, but not atropine, by guinea pig liver was observed, while the serum was without action on either of the compounds. On this basis the possibility arises that guinea pig liver contains a homatropinesterase enzyme separate from atropinesterase. It was shown that lack of atropinesterase activity in certain rabbits is not likely to be due to the presence of a naturally occurring inhibitor. It has been demonstrated that contrary to previous indications neither fresh egg white nor yolk possess atropinesterase activity. The specificity of tropinesterases was investigated and evidence was presented for the possible existence of two distinct enzymes, cocainesterase and tropacocainesterase.

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