DYNAMIC LIGHT-SCATTERING STUDY OF THE 2-DOMAIN STRUCTURE OF HUMICOLA INSOLENS ENDOGLUCANASE-V

Endoglucanase V (EG V) of Humicola insolens is composed of a catalytic domain and of a cellulose-binding domain linked by a 33 amino acid long peptide rich in Ser, Thr and Pro residues, This work describes the dynamic behavior of the two-domain structure of EG V as revealed by quasi-elastic light scattering experiments, For both the full-length and the isolated catalytic domain, the autocorrelation function is essentially described by a single relaxation mode, The equivalent hydrodynamic radius of the catalytic domain mas found to correspond precisely to the dimensions measured from the previously determined three-dimensional structure, The results obtained with the full-length protein allow a description of the two domain structure of EG V similar to that resulting from earlier studies using small angle X-ray scattering on cellulases from Trichoderma reesei. The hydrodynamic dimensions of the entire enzyme can be approximated as an ellipsoid with dimensions of 42 x 133.6 Angstrom.