Interaction of Aromatic Compounds With α-Chymotrypsin^*

?-Chymotrypsin: A Study of the Promotion of the Deacylation Reaction

“…These observations are consistent with the KIn values obtained. KIn for formyl-chymotrypsin (Table 2) agrees well with the value of 0·8 mM obtained for indole as a competitive inhibitor by Wallace, Kurtz, and Niemann (1963), showing that acylation of Ser-195 does not change the structure of the hydrophobic site. KIn for acetyl-chymotrypsin is considerably higher than that for formyl-chymotrypsin, showing that steric hindrance to complex formation is appreciable.…”

Protease I from Escherichia coli

“…This tends to indicate an extended specificity site covering several residues, as has been noted for some other proteinases [34,35]. The importance of hydrophobic binding of the substrate has been discussed in relation to the action of several mammalian enzymes including chymotrypsin [36]. The fact that a short peptide such as tetra-L-phenylalanine is very weakly hydrolyzed, also support the view that protease I has a requirement for a minimum peptide size.…”

Photophysics and activity of biological systems containing the optical probes 7-azatryptophan and its analogs

“…Chapman and Maroncelli have studied 7-azaindole fluorescence in water and in mixtures of water and diethyl ether [43]. They too observe long-wavelength, tautomer-like emission at low water concentrations.…”

“…One may ask whether the reorganization of water molecules about the solute can occur on such a slow time scale. It is important to distinguish the time scales involving reorientational dynamics of solvent molecules, which can be extremely rapid [10,43], and "diffusive redistribution" of solvent. In particular, one must distinguish between the kind of solvent reorientation that is induced by dipole moment changes in the excited state of a probe molecule and reorganization of the solvent that involves the breaking and making of X = kj + kp®; Y = k., + kpN (H) hydrogen bonds.…”

“…It has been noted that in polyalcohols such as ethylene glycol and glycerol there is a severe deviation, characterized by unusually slow tautomerization, from the good correlation of tautomerization rate with EjCSO) that is observed with monoalcohols [14]. It has been suggested that this deviation is a signature of solvents capable of donating more than one hydrogen bond per molecule and that such solvents reduce the probability of forming solute molecules with the "correct" solvation for tautomerization [14,43]. The detailed mechanism of the rate reduction peculiar to these solvents is still unknown.…”