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

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.

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ENZYME HYDROLYSIS OF PURIFIED HCG

Acta Endocrinologica ◽

10.1530/acta.0.061s219 ◽

1969 ◽

Vol 61 (1_Suppl) ◽

pp. S219

Author(s):

Carl Beling ◽

Ronald Stark

Keyword(s):

Enzyme Hydrolysis ◽

Hydrolysis Of

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Variation in Quantity of Methanol Recovered from Raisins

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/46.2.341 ◽

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.

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Novel activity of angiotensin-converting enzyme. Hydrolysis of cholecystokinin and gastrin analogues with release of the amidated C-terminal dipeptide

Biochemical Journal ◽

10.1042/bj2620125 ◽

1989 ◽

Vol 262 (1) ◽

pp. 125-130 ◽

Cited By ~ 39

Author(s):

P Dubreuil ◽

P Fulcrand ◽

M Rodriguez ◽

H Fulcrand ◽

J Laur ◽

...

Keyword(s):

Angiotensin Converting Enzyme ◽

Chloride Ion ◽

Peptide Bond ◽

Major Product ◽

Enzyme Hydrolysis ◽

Ion Concentration ◽

Converting Enzyme ◽

Rabbit Lung ◽

Hydrolysis Of

ACE (angiotensin-converting enzyme; peptidyl dipeptidase A; EC 3.4.15.1), cleaves C-terminal dipeptides from active peptides containing a free C-terminus. We investigated the hydrolysis of cholecystokinin-8 [CCK-8; Asp-Tyr(SO3H)-Met-Gly-Trp-Met-Asp-Phe-NH2] and of various gastrin analogues by purified rabbit lung ACE. Although these peptides are amidated at their C-terminal end, they were metabolized by ACE to several peptide fragments. These fragments were analysed by h.p.l.c., isolated and identified by comparison with synthetic fragments, and by amino acid analysis. The initial and major site of hydrolysis was the penultimate peptide bond, which generated a major product, the C-terminal amidated dipeptide Asp-Phe-NH2. As a secondary cleavage, ACE subsequently released di- or tri-peptides from the C-terminal end of the remaining N-terminal fragments. The cleavage of CCK-8 and gastrin analogues was inhibited by ACE inhibitors (Captopril and EDTA), but not by other enzyme inhibitors (phosphoramidon, thiorphan, bestatin etc.). Hydrolysis of [Leu15]gastrin-(14-17)-peptide [Boc (t-butoxycarbonyl)-Trp-Leu-Asp-Phe-NH2] in the presence of ACE was found to be dependent on the chloride-ion concentration. Km values for the hydrolysis of CCK-8, [Leu15]gastrin-(11-17)-peptide and Boc-[Leu15]gastrin-(14-17)-peptide at an NaCl concentration of 300 mM were respectively 115, 420 and 3280 microM, and the catalytic constants were about 33, 115 and 885 min-1. The kcat/Km for the reactions at 37 degrees C was approx. 0.28 microM-1.min-1, which is approx. 35 times less than that reported for the cleavage of angiotensin I. These results suggest that ACE might be involved in the metabolism in vivo of CCK and gastrin short fragments.

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Crocetin: A Systematic Review

Frontiers in Pharmacology ◽

10.3389/fphar.2021.745683 ◽

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.

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

Frontiers in Molecular Biosciences ◽

10.3389/fmolb.2021.780315 ◽

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.

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

Biochemical Journal ◽

10.1042/bj2370469 ◽

1986 ◽

Vol 237 (2) ◽

pp. 469-476 ◽

Cited By ~ 24

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.

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