Relationship between Active Sites and Polymerization Sites in α-Chymotrypsin^*

A Theoretical Study of the Binding of Small Molecules to a Polymerizing Protein System. A Model for Allosteric Effects*

“…The result may be generalized to a situation where a series of polymers coexist, provided no binding sites are lost in the successive polymerizations and all Km in eq 8 are identical. Sarfare et al (1966) have demonstrated that the binding of the inhibitor /3-phenylpropionic acid to q-chymotrypsin in phosphate buffer (pFI 6.1), ionic strength 0.2, is an example of this case, since weight-average molecular weights at several en-zyme concentrations were unchanged by the presence of S for this monomer -dimer-trimer system. D. A MONOMER-SINGLE HIGHER POLYMER SYSTEM WITH DIFFERENT INTRINSIC BINDING CONSTANTS.…”

Self-association of α-chymotrypsin at low ionic strength in the vicinity of its pH optimum

“…of native a-chymotrypsin (Egan et al, 1957) was assumed to apply also to iPr2P-chymotrypsin. Refractometric measurements of concentration were based on a specific refractive increment of 1.86x 104litre/g for achymotrypsin (Sarfare et al, 1966;Aune & Timasheff, 1971) and its iPr2P derivative.…”

Nuclear magnetic resonance studies of the interaction of N-acetyltryptophan with .alpha.-chymotrypsin

“…Sarfare, et al, have shown that hydrocinnamate interacts equally well with one site on the monomeric form of a-chymotrypsin, two sites on the dimer and three sites on the trimer. 23 In contrast, Faller and La Fond24 have produced evidence that proflavine binds only to the monomeric form of the protein. If one assumes that the binding sites on the putative oligomeric complexes are characterized by the same inhibitor binding constant and exert the same chemical shift effect, it can be shown that the two models predict virtually identical dependences of observed nmr effects (x) on the E0:Io concentration ratio when the value of this ratio is small.8 It is only at larger values of Eo'.Io that a distinction can be made.…”