ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
Digestion is one of the four stages through which food is processed: these are ingestion digestion, absorption and elimination. Ingestion is the act of FEEDING; digestion is the process of degrading food components into their MOLECULE constituents for use— molecules small enough to be transported across a cell MEMBRANE have to be generated. CARBOHYDRATES are broken down to simple SUGARS (principally GLUCOSE), FATS to GLYCEROL and FATTY ACIDS, PROTEINS to AMINO ACIDS) and NUCLEIC ACIDS to NUCLEOTIDES. The essential process in this is known as enzymatic hydrolysis—the addition of water to molecules by ENZYME activity, causing them to break down. The third stage, absorption (the absorptive phase) involves cells taking up the molecules presented by digestion; the final stage is elimination, the voiding of waste material.
Proteins in Cosmetics
E. Desmond Goddard, James V. Gruber in Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
It is not always possible to apply enzymatic hydrolysis directly to proteins as they are in the native form. Native, globular proteins (e.g., from soy, corn, almond) or fibrous insoluble proteins (e.g., collagen, keratins, elastin) are generally resistant to proteolysis; this is generally explained by the compact tertiary structure of the protein that protects most of the peptide bonds. In the denatured, unfolded form the peptide bonds are exposed and available for enzymatic cleavage. As native proteins in aqueous solution are in dynamic equilibrium with a number of more or less distorted forms, part of which can be considered denatured and thereby accessible to enzyme attack, the initial break of a few peptide bonds can destabilize the protein molecule and cause irreversible unfolding: in some cases (e.g., hydrolysis of egg albumin by pepsin) this mechanism allows the protease to perform the hydrolysis to a remarkable extent. More frequently, especially when covalent bonds (disulfide bonds) stabilize the native form of the protein, a preliminary partial or extended denaturation is needed to make enzymatic hydrolysis possible; this is normally achieved by heating or chemical attack, or a combination of the two.
The Potential of Microbial Mediated Fermentation Products of Herbal Material in Anti-Aging Cosmetics
Namrita Lall in Medicinal Plants for Cosmetics, Health and Diseases, 2022
Literature indicates that the most commonly observed mechanism by which fermentation transforms plant extracts is through the release of biologically active and more readily absorbed phenolics from their conjugated sugars. Glycosides are known to be hydrophilic due to the presence of a glycosyl group, which limits their application in topical cosmetics as they exhibit low skin permeability. The cleavage of glycosidic bonds to yield the aglycone form of several common phytochemicals is thought to primarily be caused by the action of enzymes such as β-glucosidases, which are particularly abundant in lactic acid bacteria. Aglycone components such as naringenin and caffeic acid tend to exhibit more hydrophobic properties and a lower molecular weight, which enables enhanced skin permeation. Alternative methods such as acidic or alkaline hydrolysis offer harsh conditions, which lead to the instability of active compounds, are not environmentally friendly and are cost intensive. This bids additional motivation for the adoption of techniques such as microbial fermentation. Similarly, enzymatic hydrolysis requires the implementation of cost-intensive purified enzymes, which is not economically feasible (Kim et al., 2010; Lee et al., 2012; Wang et al., 2016; Nam et al., 2020).
Unveiling the interaction profile of rosmarinic acid and its bioactive substructures with serum albumin
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2020
Christina Papaemmanouil, Maria V. Chatziathanasiadou, Christos Chatzigiannis, Eleni Chontzopoulou, Thomas Mavromoustakos, Simona Golic Grdadolnik, Andreas G. Tzakos
As an ester of caffeic acid and (R)-(+)3–(3,4-dihydroxyphenyl) lactic acid, rosmarinic acid consists of two structural moieties: caffeic acid and (R)-(+)3–(3,4-dihydroxyphenyl) lactic acid. (R)-(+)3–(3,4-dihydroxyphenyl) lactic acid, known as salvianic acid, a natural compound which is not yet well defined and characterised. Although, there are chemical methods for producing salvianic acid, their yield remains low14–17. The most common synthetic procedures for salvianic acid involve its precursor 3,4-dihydroxybenzaldehyde, and, after numerous reaction steps, the obtained yield is very low while is produced a large amount of efflux15,18,19. An alternative method is its isolation from Salvia miltiorrhiza where salvianic acid is the active phytochemical substance and its extraction results to low yields as well20,21. Finally, another way of producing salvianic acid is its hydrolysis from rosmarinic acid or other natural products. Both the chemical and enzymatical methods have their own limitations. The chemical hydrolysis suffers from low yields while the enzymatic hydrolysis may be more efficient, due to high regioselectivity of the enzyme, although, more expensive.
Do CO2 and oxidative stress induce cancer?: a brief study about the evaluation of PON 1, CAT, CA and XO enzyme levels on head and neck cancer patients
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2019
Murad Mutlu, M. Hakan Korkmaz, Ender Simsek, Emine Terzi, Beyza Ecem Oz Bedir, Tugba Kevser Uysal, Omer Bayir, Guleser Saylam, Ozen Ozensoy Guler
PON1 activity towards paraoxon as a substrate was quantified spectrophotometrically by the method described by Ganet al34. The reaction was followed for 2 min. at 37 °C by monitoring the appearance of p-nitrophenol at 412 nm on a Biotek (Winooski, VT, USA). The final substrate concentration during enzyme assay was 2 mM, and all rates were determined in duplicate and corrected for the non-enzymatic hydrolysis. A molar extinction coefficient (ϵ) of 17,100 M−1 cm−1 for p-nitrophenol at pH 8.0 in 100 mMTris–base buffer was used for the calculation. One unit of PON1 activity is defined as 1 μmol of p-nitrophenol formed per minute under the above assay conditions35. Enzyme units were calculated from the absorbance change36.
Isothiocyanates: cholinesterase inhibiting, antioxidant, and anti-inflammatory activity
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2018
Franko Burčul, Ivana Generalić Mekinić, Mila Radan, Patrick Rollin, Ivica Blažević
AChE/BChE inhibitory activity measurements were carried out by a slightly modified Ellman assay as described before for AChE inhibitory activity23. A typical run consisted of 180 μL of phosphate buffer (0.1 M, pH 8), 10 μL of DTNB (at a final concentration of 0.3 mM prepared in 0.1 M phosphate buffer pH 7 with 0.12 M sodium bicarbonate added for stability), 10 μL of sample solution (dissolved in EtOH), and 10 μL of AChE/BChE solution (with final concentration 0.03 U/mL). Reactants were mixed in a cuvette and reaction was initialised by adding 10 μL of acetylthiocholine iodide/butyrylthiocholine iodide (ATChI/BTChI, to reach a final concentration of 0.5 mM). As negative control, EtOH was used instead of sample solution. Non-enzymatic hydrolysis was also monitored by measurement of two blank runs for each run. In short: in the first blank, the AChE/BChE, respectively, was replaced by equivalent buffer amount and in second blank, the ATChI/BTChI, respectively, was replaced by equivalent buffer amount. All spectrophotometric measurements were performed at 405 nm and at room temperature for 6 min periods. The results are expressed as percentage inhibition of enzyme activity.
Related Knowledge Centers
- Acid Hydrolysis
- Biochemistry
- Digestive Enzyme
- Enzyme
- Hydrolysis
- Molecule
- Digestion
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- Alkaline Hydrolysis