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Biocatalysis: An introduction
Published in Grunwald Peter, Biocatalysis and Nanotechnology, 2017
At the beginning of the 19th century, G. S. Constantin Kirchhoff (1764–1833) found that starch is degraded to simple sugars by means of diluted inorganic acids. In 1835 the Swedish chemist Jöns Jakob Berzelius (1779–1848) proposed the name catalysis (from the Greek: kata: wholly, and lyein: to loosen) for the conversion of substances under mild conditions in presence of compounds seemingly not involved into the reaction, without being able to explain what really happens during catalysis. Further findings during those times were the decomposition of starch to sugars by a compound denoted as “diastase” by the French chemist Anselme Payen (1795–1878) or the digestion of flesh in presence of pepsin prepared from animal tissues by Theodor Schwann in 1836. These compounds were first named ferments until Wilhelm Kühne (1837–1900) neoterized in 1887 the term enzyme (from the Greek: en: in, and zyme: sourdough) which should be confined to ferments not needing the surroundings of a cell to develop activity. On the other hand, Louis Pasteur (1822–1895) held the view that fermentation is not possible in absence of life; however, this opinion was disproved by the discovery made by Eduard Buchner (1860–1917) during his time in the chemical laboratory of Hans von Pechmann at the University of Tübingen, and that he published in 1897 under the title “On Alcoholic Fermentation Without Yeast Cells” (original German title: “Über die alkoholische Gärung ohne Zellen”); these findings proved that all enzymes are chemical compounds not requiring any vital force to be effective. Buchner was awarded the Noble Prize for chemistry in 1907.
Biocatalysts: The Different Classes and Applications for Synthesis of APIs
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
At the beginning of the 19th century, G. S. Constantin Kirchhoff (1764–1833) found that starch is degraded to simple sugars by means of diluted inorganic acids. In 1835, the Swedish chemist Jöns Jakob Berzelius (1779–1848) proposed the name catalysis (from the Greek: kata: wholly, and lyein: to loosen) for the conversion of substances under mild conditions in presence of compounds seemingly not involved into the reaction, without being able to explain what really happens during catalysis. Further findings during those times were the decomposition of starch to sugars by a compound denoted as “diastase” by the French chemist Anselme Payen (1795–1878) or the digestion of flesh in presence of pepsin prepared from animal tissues by Theodor Schwann in 1836. These compounds were first named ferments until Wilhelm Kühne (1837–1900) neoterized in 1887 the term enzyme (from the Greek: en: in, and zyme: sourdough) which should be confined to ferments not needing the surroundings of a cell to develop activity. On the other hand, Louis Pasteur (1822–1895) held the view that fermentation is not possible in absence of life; however, this opinion was disproved by the discovery made by Eduard Buchner (1860–1917) during his time in the chemical laboratory of Hans von Pechmann at the University of Tübingen, and that he published in 1897 under the title “On Alcoholic Fermentation Without Yeast Cells” (original German title: “Über die alkoholische Gärung ohne Zellen”); these findings proved that all enzymes are chemical compounds not requiring any vital force to be effective. Buchner was awarded the Noble Prize for chemistry in 1907.
Biofabrication of Graphene Oxide Nanosheets
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2019
Atomic force microscopic (AFM) studies of graphene-based materials are carried out to find out the thickness of the synthesized graphene-based nanostructures. Figure 16.18 shows a typical AFM image of diastase enzyme-mediated rGO (DRG) (Maddinedi et al., 2017b). It is evident that the thickness of DRG sheet is 1.72 nm; that is, its sheet consists of two layers considering the thickness of single-layered graphene sheet as 0.8 nm (Fan et al., 2008; Novoselov et al., 2004). Also, one can get information on stabilizing agent present on the graphene surface compared to a flat sp2 carbon atom network (0.335 nm) (Ni et al., 2007).
Batch and fed-batch fermentation of optically pure D (-) lactic acid from Kodo millet (Paspalum scrobiculatum) bran residue hydrolysate: growth and inhibition kinetic modeling
Published in Preparative Biochemistry & Biotechnology, 2020
Rengesh Balakrishnan, Subbi Rami Reddy Tadi, Shyam Kumar Rajaram, Naresh Mohan, Senthilkumar Sivaprakasam
Powdered KMBR was added to deionized water (11.43% w/v) and 2 M HCl was used to adjust the pH to 6.0. Prior to the enzymatic hydrolysis, gelatinization was initiated by heating KMBR-water mixture at 90 °C for 20 min. After gelatinization, the pH of the slurry was readjusted to 6.0 and commercially obtained α-amylase (diastase from fungi) enzyme was added to the slurry (3% w/v). The liquefaction was carried out at 60 °C for 90 min. After the pH readjustment to 4.59, an optimized dosage of glucoamylase (97.52 GAU.g−1 of KMBR) was added to the enzyme hydrolysate. Glucoamylase (1,00,000 glucoamylase units GAU.mL−1) was purchased from Richcore Lifesciences Pvt. Ltd, Bengaluru, India. Saccharification process was carried out at temperature 45 °C for 16 h. The saccharificate was heated at 100 °C for 10 min to deactivate the enzymes after the complete conversion of enzyme hydrolysate into soluble sugars. The saccharificate was cooled to room temperature and its pH was adjusted to 7.0 using 2 N NaOH. The coarse particles were removed from the saccharificate by centrifugation at 10,000 rpm for 10 min. The clarified saccharificate served as the chief carbon source for DLA fermentation process ‘Kodo millet bran residue hydrolysate (KMBRH)’ [Note: Henceforth, ‘KMBRH’ terminology usage corresponds to the concentration of glucose in KMBRH].[2] KMBRH was concentrated using rotavapor (M/s Buchi, model: R 300, Switzerland) under vacuum with water bath at 60 °C. The concentrate (final concentration of glucose in KMBRH ≅ 400 g.L−1) was stored in bulk (pH 4) at 4 °C to prevent the microbial attack as well to maintain homogeneity.