Open AccessStudies of Glutamate Dehydrogenase
Author(s) -
Pilz Ingrid,
Sund Horst
Publication year - 1971
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1971.tb01428.x
Subject(s) - oligomer , radius of gyration , glutamate dehydrogenase , dissociation (chemistry) , chemistry , scattering , crystallography , gtp' , nucleotide , small angle x ray scattering , materials science , enzyme , polymer chemistry , physics , optics , glutamate receptor , polymer , organic chemistry , biochemistry , receptor , gene
The size and shape of beef liver glutamate dehydrogenase in the presence of the allosteric effectors GTP and NADH were investigated by X‐ray small‐angle measurements. These nucleotides cause a dissociation of the associated particles into oligomers. The radius of gyration ( R ) of the oligomer was found to be 47 Å and a pronounced subsidiary maximum was obtained as is the case with the associated particles. Comparison with theoretical scattering curves shows that the overall shape of the oligomer corresponds well to a rounded cylinder with a ratio diameter to length of 1:1.5, a length of 12.6 nm and a diameter of 8.4 nm. The relatively high value of the volume ( V = 668 nm 3 ) indicates that the oligomer is loosely built and from the height of the subsidiary maxima it must be assumed that the oligomer contains larger voids. It is concluded that after interaction with GTP and NADH the conformation of glutamate dehydrogenase is not changed to a great extent although these nucleotides favor the dissociation into the oligomers. Based on the comparison of calculated scattering curves the eclipsed model for the oligomer proposed by Eigenberg and Reisler can be excluded. The calculated curve for the more staggered model has some similarities but does not coincide completely with the experimental scattering curve.