〈1055〉 Biotechnology-Derived Articles—Peptide Mapping

2021 ◽  
Keyword(s):  
Amylase ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 38-49
Author(s):  
Connie Pontoppidan ◽  
Svend G. Kaasgaard ◽  
Carsten P. Sønksen ◽  
Carsten Andersen ◽  
Birte Svensson

Abstract The industrial thermostable Bacillus licheniformis α-amylase (BLA) has wide applications, including in household detergents, and efforts to improve its performance are continuously ongoing. BLA during the industrial production is deamidated and glycated resulting in multiple forms with different isoelectric points. Forty modified positions were identified by tandem mass spectrometric peptide mapping of BLA forms separated by isoelectric focusing. These modified 12 asparagine, 9 glutamine, 8 arginine and 11 lysine residues are mostly situated on the enzyme surface and several belong to regions involved in stability, activity and carbohydrate binding. Eight residues presumed to interact with starch at the active site and surface binding sites (SBSs) were subjected to mutational analysis. Five mutants mimicking deamidation (N→D, Q→E) at the substrate binding cleft showed moderate to no effect on thermostability and k cat and K M for maltoheptaose and amylose. Notably, the mutations improved laundry wash efficiency in detergents at pH 8.5 and 10.0. Replacing three reducing sugar reactive side chains (K→M, R→L) at a distant substrate binding region and two SBSs enhanced wash performance especially in liquid detergent at pH 8.5, slightly improved enzymatic activity and maintained thermostability. Wash performance was most improved (5-fold) for the N265D mutant near substrate binding subsite +3.


2006 ◽  
Vol 281 (33) ◽  
pp. e27-e28
Author(s):  
Nicole Kresge ◽  
Robert D. Simoni ◽  
Robert L. Hill
Keyword(s):  

Amino Acids ◽  
2021 ◽  
Author(s):  
Magdalena Widgren Sandberg ◽  
Jakob Bunkenborg ◽  
Stine Thyssen ◽  
Martin Villadsen ◽  
Thomas Kofoed

AbstractGranulocyte-macrophage colony-stimulating factor (GM-CSF) is a cytokine and a white blood cell growth factor that has found usage as a therapeutic protein. During analysis of different fermentation batches of GM-CSF recombinantly expressed in E. coli, a covalent modification was identified on the protein by intact mass spectrometry. The modification gave a mass shift of + 70 Da and peptide mapping analysis demonstrated that it located to the protein N-terminus and lysine side chains. The chemical composition of C4H6O was found to be the best candidate by peptide fragmentation using tandem mass spectrometry. The modification likely contains a carbonyl group, since the mass of the modification increased by 2 Da by reduction with borane pyridine complex and it reacted with 2,4-dinitrophenylhydrazine. On the basis of chemical and tandem mass spectrometry fragmentation behavior, the modification could be attributed to crotonaldehyde, a reactive compound formed during lipid peroxidation. A low recorded oxygen pressure in the reactor during protein expression could be linked to the formation of this compound. This study shows the importance of maintaining full control over all reaction parameters during recombinant protein production.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Teodora Bavaro ◽  
Sara Tengattini ◽  
Refaya Rezwan ◽  
Enrica Chiesa ◽  
Caterina Temporini ◽  
...  

AbstractExogenous application of human epidermal growth factor (hEGF) stimulates epidermal wound healing. The aim of this study was to develop bioconjugates based on hEGF mimicking the protein in its native state and thus suitable for tissue engineering applications, in particular for treating skin-related disorders as burns. Ribonuclease A (RNase A) was used to investigate a number of different activated-agarose carriers: cyanogen bromide (CNBr)-activated-agarose and glyoxyl-agarose showed to preserve the appropriate orientation of the protein for receptor binding. EGF was immobilized on these carriers and immobilization yield was evaluated (100% and 12%, respectively). A peptide mapping of unbound protein regions was carried out by LC–MS to take evidence of the residues involved in the immobilization and, consequently, the flexibility and surface accessibility of immobilized EGF. To assess cell proliferative activities, 10, 25, 50, and 100 ng/mL of each immobilized EGF sample were seeded on fibroblast cells and incubated for 24, 48 and 72 h. The immobilized growth factor showed significantly high cell proliferative activity at 50 and 100 ng/mL compared to control and soluble EGF. Although both of the immobilized samples show dose-dependency when seeded with high number of fibroblast cells, CNBr-agarose-EGF showed a significantly high activity at 100 ng/mL and 72 h incubation, compared to glyoxyl-agarose-EGF.


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