Vinsamlegast notið þetta auðkenni þegar þið vitnið til verksins eða tengið í það: http://hdl.handle.net/1946/17816
Over the past four decades, enzymes have become valuable catalysts for industrial and biotechnological purposes. Like other proteins, mesophilic enzymes are only marginally stable at ambient conditions. However, they are usually catalytically more efficient than commonly used thermophilic enzymes, thereby justifying their application. Utilization of mesophilic enzymes is only practical if they are stabilized against otherwise inactivating and unfolding conditions. It is well documented that glycoproteins are usually more stable than unglycosylated proteins. In this study, three trypsin species were synthesized. D-glucosamine and 1:5/ 1:10 trypsin-to-chitooligosaccharide (or partially acetylated poly-1,4-β-D-glucosamine) was conjugated and cross-linked to bovine trypsin, respectively, via binary carbodiimide/succinimide ester conjugation. The degree of conjugation and sizes of the cross-linked enzymes was determined. D-glucosamine was found to conjugate, on average, to 12 residues on trypsin and the two ratios of cross-linked enzyme were found to form huge and polydisperse complexes with hydrodynamical radii from, on average, from 218 to 330 nm for 1:5 and 1:10 cross-linked trypsin, respectively. The trypsin species gave significantly higher T50% values, resistance against thermal inactivation and autolysis increased, thermal and storage stability improved, however, stability against urea inactivation was not changed, compared with native trypsin. The proteolytic activity against azocasein improved for the cross-linked trypsins but was slightly reduced for D-glucosamine conjugated trypsin, compared with native trypsin. The species were found to become basophilic upon conjugation and cross-linking. D-glucosamine conjugated trypsin was found to be slightly structurally altered, which displayed 1.2 times higher catalytic efficiency (kcat/Km) than native trypsin against the substrate L-BAPNA.
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