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Macronutrients
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
The name of an enzyme has two parts. The first part is the name of the substrate, and the second part is terminated with a suffix -ase (54). For example, protease is an enzyme of the substrate protein. For the international nomenclature, the name of an enzyme is preceded by the two letters EC (Enzyme Commission) followed by four numbers. For example, E.C.2.7.1.1. The first number denotes one of the six main classes: oxidoreductases, transferases, hydrolases, lyases, isomerases, and ligases. The second number denotes the subclass and the third number denotes the sub-subclass. The last number denotes the serial number of the enzyme in its sub-subclass (53–54). Enzymes are classified based on the reactions they catalyze into six classes cited above. Oxidoreductases such as glutathione reductase, lactate dehydrogenase, and glucose-6-phosphate dehydrogenase are the enzymes that catalyze oxidation-reduction reactions of their substrates. Transferases transfer a functional group between two substrates such as a methyl or phosphate group. Hydrolases catalyze the hydrolysis reactions of carbohydrates, proteins, and esters. Lyases cleave various chemical bonds by other means than hydrolysis and oxidation for the formation of double bonds. Isomerases are involved in isomerization of substrate where interconversion of cis-trans isomers is implicated. Ligases such as alanyl-t-RNA synthetase, glutamine synthetase, and DNA ligases join together two substrates with associated hydrolysis of a nucleoside triphosphate (53–54).
Honey-Based Polyphenols: Extraction, Quantification, Bioavailability, and Biological Activities
Published in Megh R. Goyal, Arijit Nath, Rasul Hafiz Ansar Suleria, Plant-Based Functional Foods and Phytochemicals, 2021
Csilla Benedek, John-Lewis Zinia Zaukuu, Zsanett Bodor, Zoltan Kovacs
Although there are resins (like Oasis HLB) that are more efficient for polar compounds (gallic acid can be retained), yet their performance is generally lower for less polar substances (like quercetin or kaempferol). Istasse et al. [46] confirmed the formation of cis isomers from the trans polyphenol standards. The cis isomers were identified by comparing their spectra with the spectra of the standard solutions in HPLC-DAD and LC-UV-MS. The authors concluded that cis isomers can be formed even in the absence of light, even though the light was previously considered to be essential for this transformation. They confirmed that the causes are not yet clear, as isomerization can be induced by simple exposure to ambient temperature in methanolic solution or an unknown reaction with the adsorbent [43].
Chemopreventive Agents
Published in David E. Thurston, Ilona Pysz, Chemistry and Pharmacology of Anticancer Drugs, 2021
Due to lycopene’s molecular size, and carbon and hydrogen content, it is highly nonpolar and virtually insoluble in water but will dissolve in organic solvents and oils which explains why lycopene-containing food products will stain most plastics. Also, due to the constraints of the eleven conjugated double bonds, lycopene molecules are long and straight. Each conjugated double bond reduces the energy required for electrons to transition to higher energy states, thus allowing the molecule to absorb visible light of longer wavelengths. As it contains eleven conjugated double bonds, lycopene absorbs all but the longest wavelengths of visible light, causing it to appear deep red. These conjugated double bonds also provide the molecule’s antioxidant activity. While plants and photosynthetic bacteria naturally produce all-trans lycopene, a total of 72 geometric isomers of the molecule are sterically possible. When exposed to heat or light, the molecule can undergo isomerization to any number of these cis isomers, which have a bent shape compared to the linear form of the all-trans isomer. Theoretical studies have suggested different stabilities for the various isomers, with the all-trans and 5-cis isomers having the greatest predicted stability.
Cyclophilin inhibition as a potential treatment for nonalcoholic steatohepatitis (NASH)
Published in Expert Opinion on Investigational Drugs, 2020
Daren R. Ure, Daniel J. Trepanier, Patrick R. Mayo, Robert T. Foster
We have described the primary ways in which the three best-known cyclophilin isoforms, cyclophilins A, B and D, participate in pathophysiological activities prevalent in NASH – dysregulated mitochondrial metabolism, mPT-mediated cell death, inflammatory cell recruitment and activation, and promotion of fibrotic collagen production and maturation. These activities are not unique to NASH or liver diseases; they have been studied in even greater detail in other organ systems and disorders. For example, most of the understanding of mPT has come from studies of ischemia-reperfusion injury in myocardial infarction. Cardiovascular disorders also have been most prominent in deciphering cyclophilin inflammatory activities. Neurological injury is an area of great interest as well. Moreover, fourteen other cyclophilin isoforms exist in the human proteome, suggesting many other regulatory roles. The broad functionality of prolyl isomerization is what links all these disparate activities.
Deamidation and isomerization liability analysis of 131 clinical-stage antibodies
Published in mAbs, 2019
Xiaojun Lu, R. Paul Nobrega, Heather Lynaugh, Tushar Jain, Kyle Barlow, Todd Boland, Arvind Sivasubramanian, Maximiliano Vásquez, Yingda Xu
Deamidation and isomerization modifications rely on sufficient chromatographic separation for identification. Deamidation modifications, having a mass shift of + 1 Da can be isotopically resolved using the Q Exactive, even when poor chromatographic separation exists. Isomerization modifications do not have this advantage and can be overlooked when chromatographic peak separation is poor. This separation relies on several factors, including peptide hydrophobicity, conformation, sequence position, the specific gradient and column being used. We find that the method used here can sufficiently resolve isomerization (Fig S9) and deamidation (Fig S10) modifications occurring on long peptides, suggesting that our method is generally applicable. We also note that the chromatographic advantage of using a UPLC system over an HPLC system has pronounced resolution differences (Fig S10) that aid in making these identifications possible.
Excipients in parenteral formulations: selection considerations and effective utilization with small molecules and biologics
Published in Drug Development and Industrial Pharmacy, 2018
Bindhu Madhavi Rayaprolu, Jonathan J. Strawser, Gopal Anyarambhatla
Certain products may also be susceptible to isomerization. Dextrose in fructose has been demonstrated to form 5-hydroxymethyl furfuraldehyde post autoclaving. This impurity may react with a primary amino group to form a schiff base and cause a colored appearance [38]. In addition to isomerization, polymerization may also occur. Polymerization may be promoted by the type of excipient present. The polymerization event may be facilitated by environmental factors and leads to intermolecular reactions and a higher molecular species [35]. Lastly, primary amines may undergo a Maillard reaction when in the presence of glycosidic hydroxyl groups, such as dextrose [35].