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.
Probiotics and their Effect on Maternal and Neonatal Health
Martin Colin R, Derek Larkin in Probiotics in Mental Health, 2018
Probiotics are a preparation containing viable, defined microorganisms in sufficient numbers to alter microflora through implantation or colonization in a compartment of the host, thus exerting beneficial health effects on the host (Havenaar and Huis In’t Veld, 1992; Schrezenmeir and de Vrese, 2001). According to Roberfroid (2007) probiotics are a dietary carbohydrate that is resistant to:Gastric acidity.Hydrolysis by mammalian enzymes.Gastro Intestinal (GI) absorption.Fermentation by intestinal microflora.
Biology of microbes
Philip A. Geis in Cosmetic Microbiology, 2006
For heterotrophs, catabolism can easily be conceptualized as three interrelated stages. The first stage breaks down large molecules and polymers such as carbohydrates, proteins, and lipids. The chemical process is usually via hydrolysis. Carbohydrates are broken down into monosaccharides, proteins into amino acids, and lipids into glycerol and fatty acids. During the second stage, these breakdown compounds are further broken down into even simpler molecules such as acetyl CoA and pyruvate (during monosaccharide, glycerol, and fatty acid breakdown), and tricarboxylic acid cycle intermediates (during amino acid breakdown). During this second stage, the production of ATP and electron carriers such as nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FADH2) occurs. Finally, these simple molecules are completely oxidized into CO2 and additional amounts of ATP, NADH, and FADH2 are produced. The electron carriers are further oxidized via the electron transport chain to yield large amounts of ATP, producing water and CO2 in the process.
Discovery of a novel Aurora B inhibitor GSK650394 with potent anticancer and anti-aspergillus fumigatus dual efficacies in vitro
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Yuhua He, Wei Fu, Liyang Du, Huiqiao Yao, Zhengkang Hua, Jinyu Li, Zhonghui Lin
It is well known that ATP is the primary carrier of energy in cells. Upon hydrolysis, it releases energy from the chemical bonds to fuel cellular processes. For example, ATP hydrolysis by motor proteins or DNA helicases can induce conformational changes and thus drive the translocation of these proteins. In addition, the protein kinases regulate various biological processes by transferring a phosphate group from ATP to amino acid residues like serine, threonine, or tyrosine. Interestingly, the mitotic kinases Aurora B, Haspin, and Bub132 also possess intrinsic ATPase activity, producing free inorganic phosphate. It is currently unknown whether this energy-consuming activity has a physiological role in cells, further studies are needed to address this potentially interesting question.
Development of stabilized tenofovir disoproxil tablet: degradation profile, stabilization, and bioequivalence in beagle dogs
Published in Drug Development and Industrial Pharmacy, 2018
Ga-Hui Oh, Joo-Eun Kim, Young-Joon Park
Hydrolysis is the most common process among factors associated with degradation such as pH and oxidation conditions. Hydrolysis rates depend on exposure to acidic or basic conditions and the drug concentrations [17,18]. The susceptibility of the test drug substance to hydrolysis and oxidation was evaluated in 0.01 N HCl, 0.01 N NaOH, and 3% H2O2 solutions. After 24 h, the TD tablet was more stable in the acidic solution than it was in the alkali and H2O2 solutions (Figure 2(B)). The higher instability of TD under basic conditions is attributable to the presence of P–O and C–O bonds, which are specifically resistant to attacks by the nucleophiles in alkaline solution. In addition, the oxidative degradation of TD involves an electron transfer mechanism that forms reactive anions and cations. Especially, amines, sulfides, and phenols are liable to electron transfer oxidation [18]. Therefore, the generation of dimers by oxidation may be due to the presence of amines in the tenofovir structure. The results of the degradation profiles indicate that TD is readily converted to tenofovir and tenofovir monoester in stress conditions, resulting in a similar response as that of TDF to oxidative, thermal, and hydrolysis conditions [19].
A review on parenteral delivery of peptides and proteins
Published in Drug Development and Industrial Pharmacy, 2019
Divisha Jain, S. Shahe Mahammad, Pirthi Pal Singh, Ravinder Kodipyaka
Peptides and proteins contain multiple functional groups, many of which can undergo some type of chemical modification or damage. To stabilize the formulation from degradation, a detailed understanding of these degradation pathways is required. Peptides/proteins are susceptible to hydrolysis, oxidation, and photodegradation. Hydrolysis is a general term for a class of chemical reactions in which bonds are broken by the addition of water. The reactions associated with the hydrolysis process include deamidation, aspartate isomerization, proteolysis, β-elimination, and others. The oxidation process is exacerbated in presence of metal-ion and some excipients such as polysorbates. The use of antioxidants as well as chelating agent can be useful to bridle the oxidation degradation.
Related Knowledge Centers
- Fructose
- Glucose
- Hydroxide
- Solvation
- Sucrose
- Carbohydrate
- Saccharification
- Salt
- Acid Strength
- Self-Ionization of Water