title: Enhancement of biological reactions on cell surfaces via macromolecular crowding.
abstract: The reaction of macromolecules such as enzymes and antibodies with cell surfaces is often an inefficient process, requiring large amounts of expensive reagent. Here we report a general method based on macromolecular crowding with a range of neutral polymers to enhance such reactions, using red blood cells (RBCs) as a model system. Rates of conversion of type A and B red blood cells to universal O type by removal of antigenic carbohydrates with selective glycosidases are increased up to 400-fold in the presence of crowders. Similar enhancements are seen for antibody binding. We further explore the factors underlying these enhancements using confocal microscopy and fluorescent recovery after bleaching (FRAP) techniques with various fluorescent protein fusion partners. Increased cell-surface concentration due to volume exclusion, along with two-dimensionally confined diffusion of enzymes close to the cell surface, appear to be the major contributing factors.
authors.affiliation: 1] Centre for Blood Research, University of British Columbia, 2350 Health Sciences Mall, Life Sciences Centre, Vancouver, British Columbia, Canada V6T 1Z3 [2] Department of Pathology and Laboratory Medicine, University of British Columbia, 2350 Health Sciences Mall, Life Sciences Centre, Vancouver, British Columbia, Canada V6T 1Z3.
authors.forename: Rafi
authors.initials: R
authors.lastname: Chapanian
authors.affiliation: 1] Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1 [2] Centre for High-Throughput Biology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.
authors.forename: David H
authors.initials: DH
authors.lastname: Kwan
authors.affiliation: Centre for Blood Research, University of British Columbia, 2350 Health Sciences Mall, Life Sciences Centre, Vancouver, British Columbia, Canada V6T 1Z3.
authors.forename: Iren
authors.initials: I
authors.lastname: Constantinescu
authors.affiliation: Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1.
authors.forename: Fathima A
authors.initials: FA
authors.lastname: Shaikh
authors.affiliation: Centre for Blood Research, University of British Columbia, 2350 Health Sciences Mall, Life Sciences Centre, Vancouver, British Columbia, Canada V6T 1Z3.
authors.forename: Nicholas A A
authors.initials: NA
authors.lastname: Rossi
authors.affiliation: 1] Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1 [2] Centre for High-Throughput Biology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3 [3] Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3.
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Withers
authors.affiliation: 1] Centre for Blood Research, University of British Columbia, 2350 Health Sciences Mall, Life Sciences Centre, Vancouver, British Columbia, Canada V6T 1Z3 [2] Department of Pathology and Laboratory Medicine, University of British Columbia, 2350 Health Sciences Mall, Life Sciences Centre, Vancouver, British Columbia, Canada V6T 1Z3 [3] Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1.
authors.forename: Jayachandran N
authors.initials: JN
authors.lastname: Kizhakkedathu
mesh_terms: D000017:ABO Blood-Group System / Q000737:chemistry*; D003911:Dextrans / Q000737:chemistry; D004058:Diffusion; D004912:Erythrocytes / Q000737:chemistry* / Q000166:cytology; D005079:Excipients / Q000737:chemistry*; D005362:Ficoll / Q000737:chemistry; D036681:Fluorescence Recovery After Photobleaching; D017930:Genes, Reporter; D005990:Glycerol / Q000737:chemistry; D006026:Glycoside Hydrolases / Q000737:chemistry*; D006801:Humans; D006868:Hydrolysis; D018613:Microscopy, Confocal; D011108:Polymers / Q000737:chemistry; D011205:Povidone / Q000737:chemistry; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000017:ABO Blood-Group System; D003911:Dextrans; D005079:Excipients; D011108:Polymers; D011993:Recombinant Fusion Proteins; C043941:polyglycerol; D005362:Ficoll; D006026:Glycoside Hydrolases; D011205:Povidone; D005990:Glycerol