Galactoside-binding Lectins from Plant and Animal Origin

6 Galactoside-binding Lectins from Plant and Animal Origin 

7 Sialidase from Clostridium Perfringens (Wild Type and Mutants) 

The presence of a number of CIDNP-sensitive amino acids on the protein surface can enable the detection of conformational alterations resulting from single site mutations. This has been demonstrated for wild-type forms and various mutants of EcorL and of the sialidase of Clostridium perfringens [5, 7], Sialidase of C. perfringens is larded with CIDNP-responsive amino acid residues. Therefore, these residues have been used as valuable sensors in NMR and modelling studies in which CIDNP-spectra of the sialidase wild type and various mutants are compared and correlated with modelled structures. 

Starting with the crystal structure of the bacterial sialidase of Salmonella typhi-murium [60] which is used as a framework, the knowledge based homology modelling produces a set of energy-minimised conformations for the small sialidase of C. 

In addition to the wild-type enzyme the impact of introducing amino acid substitutions by site-directed mutagenesis has been theoretically and experimentally delineated as a further test of the model structure. Changes in surface accessibilities of widely separated residues affected by a Tyr/Phe- or a Cys/Ser-substitution could be measmed and calculated. This leads to the conclusion that conformational changes of mutant enzymes relative to the wild-type form should not be underestimated. 

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