Tritium NMR spectroscopy of ligand binding to maltose-binding protein

Journal Article · Tue Jun 04 00:00:00 EDT 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00236a027· OSTI ID:5046562

Gehring, K; Williams, P G; Pelton, J G; Morimoto, H; Wemmer, D E ^[1]

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1. Lawrence Berkeley Lab., CA (United States)

Tritium-labeled {alpha}- and {beta}-maltodextrins have been used to study their complexes with maltose-binding protein (MBP), a 40-kDa bacterial protein. Five substrates, from maltose to maltohexaose, were labeled at their reducing ends and their binding studied. Tritium NMR specctroscopy of the labeled sugars showed large upfield chamical shift changes upon binding and strong anomeric specficity. At 10{degrees}C, MBP bound {alpha}-maltose with 2.7 {plus minus} 0.5-fold higher affinity than {beta}-maltose, and, for longer maltodextrins, the ratio of affinities was even larger. The maximum chemical shift change was 2.2 ppm, suggesting that the reducing end of bound {alpha}-maltodextrin makes close contact with an aromatic residue in the MBP-binding site. Experiments with maltotriose (and longer maltodextrins) also revealed the presence of two bound {beta}-maltotriose resonances in rapid exchange. The authors interpret these two resonances as arising from two distinct sugar-protein complexes. In one complex, the {beta}-maltodextrin is bound by its reducing end, and, in the other complex, the {beta}-maltodextrin is bound by the middle glucose residue(s). This interpretation also suggests how MBP is able to bind both linear and circular maltodextrins.

• DOE Contract Number: AC03-76SF00098; FG05-86ER75281
• OSTI ID: 5046562
• Journal Information: Biochemistry; (United States), Vol. 30:22; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
DEXTRIN
BIOCHEMICAL REACTION KINETICS
MEMBRANE PROTEINS
NUCLEAR MAGNETIC RESONANCE
LIGANDS
MALTOSE
PROTONS
STRUCTURAL MODELS
TRITIUM COMPOUNDS
BARYONS
CARBOHYDRATES
DISACCHARIDES
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HYDROGEN COMPOUNDS
KINETICS
MAGNETIC RESONANCE
NUCLEONS
OLIGOSACCHARIDES
ORGANIC COMPOUNDS
POLYSACCHARIDES
PROTEINS
REACTION KINETICS
RESONANCE
SACCHARIDES
550201* - Biochemistry- Tracer Techniques