Fluorine-19 nuclear magnetic resonance study of the binding of trifluoroacetylglucosamine oligomers to lysozyme

Biological Magnetic Resonance

“…This result suggests that the N-trifluoroacetylated tetramer occupies positions A, B, and C at the active site, with the nonreducing end residue protruding into solution (Millett and Raftery, 1972b). …”

“…Although experimental details were scant it appears that the rate of dissociation ofthe N-TFA-sugar-enzyme complex is slightly faster than the rate for the N-acetylsugar-enzyme complex. Both rates are approximately 10 4 S-1, rapid enough to assure "fast-exchange" averaging of chemical shifts, a condition assumed by workers collecting the data given in Table III. FMR has been used to study the binding of N-trifluoroacetylglucosamine oligomers to lysozyme (Millett and Raftery, 1972b). For the dimer, trimer, and tetramer exchange between free and enzyme-bound saccharide was not in the fast-exchange limit at normal temperatures and sample temperatures of 50° to 65°C were necessary to achieve this condition.…”

“…Using the paramagnetic shift effect of cobalt II, it was demonstrated that the trimer occupies subsites A, B, and C with the reducing end in site C (Millett and Raftery, 1972b). The reducing-end trifluoroacetyl group in a-N-trifluoroacetyl glucosamine (monomer) and the N-trifluoroacetylated dimer both show large upfield shifts induced by the enzyme, but the reducing-end TF A group of the trimer was shifted downfield.…”

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“…In early works, Dwek [121] and Gerig [122] reported the use of F moieties to probe interactions of oxy-and deoxyhemoglobin with cofactors such as diphosphoglycerate (DPG) under differential protonation [123]. Trifluoroacetylated chitotriose and N-trifluoroacetylglucosamine were used to probe active sites in lysozyme [124]. Many fluoro sugars have been used to study enzyme specificity, substrates, or inhibitors of enzymes such as glycogen phosphorylase and glucosidases [125][126][127].…”

“…As such, fluorosugars were widely used to explore mechanisms of enzyme activity [124,126,360]. We adopted a different strategy by including 19 F into the aglycon moiety of a substrate to detect b-galactosidase activity (Figs.…”