Carbohydrate-polypeptide contacts in the antibody receptor CD16A identified through solution NMR spectroscopy.
 

Carbohydrate-polypeptide contacts in the antibody receptor CD16A identified through solution NMR spectroscopy.

Carbohydrate-polypeptide contacts in the antibody receptor CD16A identified through solution NMR spectroscopy.

Biochemistry. 2017 Jun 14;:

Authors: Subedi GP, Falconer DJ, Barb AW

Abstract
Asparagine-linked carbohydrates (N-glycans) are a common modification of eukaryotic proteins that confer multiple properties including the essential stabilization of therapeutic monoclonal antibodies. Here we present a rapid and efficient strategy to identify N-glycans that contact polypeptide residues and apply the method to profile the five N-glycans attached to the human antibody receptor CD16A (Fc gamma ??receptor IIIA). Human embryonic kidney 293S cells expressed CD16A with [13CU]-labeled N-glycans using standard protein expression techniques and medium supplemented with 3 g/L [13CU]-glucose. Anomeric resonances on the protein-linked N-acetylglucosamine residue at the reducing end of the glycan are particularly well suited to studies of multiply-glycosylated N-glycoproteins because only one reducing end and nitrogen-linked residue is present in each N-glycan. Correlations between anomeric 1H1-13C1 nuclei on the reducing end residue generate crosspeaks in a conventional 2d heteronuclear single quantum coherence NMR experiment that appear in a region of the spectrum devoid of other carbohydrate peaks or background protein signals. Two N-glycan peaks corresponding to the N45 and N162 N-glycans were dispersed from the rapidly averaged peaks corresponding to the N38, N74 and N169 N-glycans. We used a combination of NMR and 1 micro?second all-atom computational simulations to identify unexpected contacts between the N45 N-glycan and CD16A polypeptide residues.


PMID: 28613884 [PubMed - as supplied by publisher]



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