Reversible Zymo-Hydrolysis a Chronology of Enzymatic Peptide Synthesis
Willi Kullmann in Enzymatic Peptide Synthesis, 1987
The possibility of the participation of hydrolases in not only the degradation but also the assembly of biological macromolecules was first suggested by the phenomenon of the so-called “reversible zymo-hydrolysis”, a term introduced in 1898 by A. C. Hill to designate the maltase-catalyzed synthesis of maltose from glucose.3 Indeed, the earliest reports on glycosidase-, lipase-, and protease-mediated syntheses of glycosides, fats, and peptides were published as early as 18993 and 1901,4,5 respectively, and a further series of studies dealing with enzymatic syntheses of these biomolecules were performed during the following decades (for reviews see References 6 and 7). In contrast, as our present picture of nucleic acid chemistry has evolved only since the early 1950s, it comes as no surprise that the first report of a nuclease-catalyzed formation of oligonucleotides did not appear until 1955.8
Therapeutic Potential of Anthocyanin Against Diabetes
Hafiz Ansar Rasul Suleria, Megh R. Goyal in Health Benefits of Secondary Phytocompounds from Plant and Marine Sources, 2021
Digestion of carbohydrates inside our body occurs in a successive way with α-amylase acting initially on starch trailed by α-glucosidase to produce dietary glucose. Once the food is ingested, starch is acted upon by α-amylases (both salivary and pancreatic) and four small intestinal mucosal α-glucosidase subunits [57], and at an inner α-1,4 glucosidic linkages via an endo mechanism thereby producing linear and branched maltooligosaccharides [55]. Maltase-glucoamylase and sucrose-isomaltase (the two membrane-bound protein complexes), and mucosal α-glucosidases are exo-type starch hydrolyzing enzymes [65, 68] that produce glucose by hydrolyzingα-1,4 glucosidic linkages opposite to the reducing end of dextrins already degraded by α-amylase [6, 27, 29]. Apart from illustrious maltase activity, the C-terminal subunit (maltase-glucoamylase) is named as isomaltase because of its action on long-chain oligomers [54] whereas the N-terminal subunit (sucrose isomaltase) is named as isomaltase because of its debranching activity [28].
Inhibiting the Absorption of Dietary Carbohydrates and Fats with Natural Products
Christophe Wiart in Medicinal Plants in Asia for Metabolic Syndrome, 2017
Delaying intestinal glucose absorption is an important therapeutic strategy to fight metabolic syndrome because it decreases postprandial glycemia, decreases insulin resistance, evokes mild loss of body weight, and improves serum lipid profiles.55 Aqueous extract from fruits of Siraitia grosvenorii (Swingle) C. Jeffrey ex A.M. Lu & Z.Y. Zhang given intragastrically and prophylactically to Wistar rats at a single dose of 0.1 g/kg decreased postprandial glycaemia when administered with oral load of maltose.56 From this extract, a mixture of triterpene glycosides at a dose of 0.1 g/kg decreased maltose-induced, postprandial glycaemia to 70% after 30 minutes.56 This fraction inhibited in vitro the enzymatic activity of rat intestinal maltase with an IC50 value equal to 5 mg/mL.56 From this fraction, the triterpene saponins mogroside V. (Figure 1.11) inhibited rat-intestinal maltase in vitro with an IC50 of 18 mg/mL.56 It should be noted that peak blood glucose values in rats are obtained much earlier (15–45 minutes) than in human subjects (around 60 minutes).57 Being nontoxic, the fruits of Siraitia grosvenorii (Swingle) C. Jeffrey ex A.M. Lu & Z.Y. Zhang could, be incorporated in the diet of subjects with metabolic syndrome. Clinical studies in this direction are needed.
Subcutaneous immunoglobulin 16.5% for the treatment of pediatric patients with primary antibody immunodeficiency
Published in Expert Review of Clinical Immunology, 2023
Sudhir Gupta, Roger H. Kobayashi, Jiří Litzman, Laurel Cherwin, Sonja Hoeller, Huub Kreuwel
The excipient maltose is used as the stabilizer for SCIG 16.5% at a target concentration of 7.4% to achieve osmolality and assure IgG stability [57]. Maltose is a water-soluble disaccharide. Unlike sucrose, maltose is metabolized by kidney cells [71–73]. The SCIG and IVIG products stabilized with maltose are well tolerated [74]. This is believed to occur as because maltase, the enzyme responsible for catalyzing the hydrolysis of the disaccharide maltose to glucose, is present in the brush border of proximal convoluted renal tubules [74]. Nonclinical research has demonstrated that maltose is mostly metabolized with <5% excreted unchanged, unlike sucrose in which >60% may be excreted unchanged in the urine [75]. The conversion of maltose to glucose occurs intracellularly in the kidney; thus, maltose does not increase glucose levels in the blood, even in diabetic patients [76]. Falsely elevated blood glucose readings may occur during and after the infusion of SCIG 16.5% stabilized with maltose with some glucometer and test strip systems. When administering SCIG 16.5%, measure blood glucose with a glucose-specific method.
The challenges of oral drug delivery via nanocarriers
Published in Drug Delivery, 2018
Jonas Reinholz, Katharina Landfester, Volker Mailänder
However, the oral dosage form also has several drawbacks. Before the orally applied drug is able to reach its target, in most instances it needs to overcome multiple compartments of the human body, which is challenging for a broad spectrum of pharmaceuticals, especially for protein- or peptide-based ones. In general, the first major challenge for the drug after ingestion is surviving the harsh acidic pH value in the stomach. In addition, the proteases pepsin and cathepsin start to digest proteins into peptides. Once the drug surpasses the stomach and enters the small intestine via the duodenum, it faces the major enzymatic digestion machinery of the human body. Oligosaccharides and maltose are degraded into glucose, fructose, galactose, and mannose via sucrase, maltase, and lactase. Lipids are cleaved into glycerol and fatty acids via the pancreatic triacylglycerol lipase and carboxyl ester lipase. Peptides are digested into amino acids via trypsin, chymotrypsin, carboxypeptidase, dipeptidase, and aminopeptidase.
A Review on Biosynthesis, Analytical Techniques, and Pharmacological Activities of Trigonelline as a Plant Alkaloid
Published in Journal of Dietary Supplements, 2018
Neda Mohamadi, Fariba Sharififar, Mostafa Pournamdari, Mehdi Ansari
Serum glucose is increased by increasing intestinal maltase and α-amylase in diabetic patients (Hamden et al., 2013). Biochemical studies support hypoglycemic activity of TRG that mimics the insulin function and inhibits the intestinal α-amylase activity (Gad et al., 2006). TRG significantly decreased the blood sugar, cholesterol, and triglyceride levels of diabetic rats, while the insulin level, nitric oxide and malondialdehyde content, and antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) exhibited normal levels in treated rats (Zhou, Zhou, & Zeng, 2013; Subramanian & Prasath, 2014). Therefore, delay in glucose absorption via the inhibition of maltase and α-amylase in the intestine is one of the therapeutic mechanisms proposed for drug-treated diabetic patients (Puri et al., 2011).
Related Knowledge Centers
- Cellular Respiration
- Glucose
- Glycogen
- Polysaccharide
- Maltose
- Α-Glucosidase
- Sucrase-Isomaltase
- Maltase-Glucoamylase
- Glycoside Hydrolase Family 13
- Adenosine Triphosphate