ISSN:
1432-1327
Keywords:
Key words Proteinases
;
Aluminum
;
Allosteric modulation
;
Metal pollution
;
Alzheimer's disease
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract The effect of aluminum ions on the binding properties of α-chymotrypsin has been studied. The results show that aluminum does not affect the catalytic rate constant k cat, but it acts as an enzyme activator favoring the binding of the substrate to the catalytic site (i.e. decreasing K m). Furthermore, aluminum binding to α-chymotrypsin displays about a threefold decrease in its affinity for the macromolecular inhibitor bovine pancreatic trypsin inhibitor (BPTI). Altogether, the different effect of aluminum on the binding of synthetic substrates (e.g. N-α-benzoyl-l-tyrosine ethyl ester, BTEE) and macromolecular inhibitors (e.g. BPTI) to α-chymotrypsin suggests the occurrence of an aluminum-linked conformational change in the enzyme molecule which brings about a marked structural change at the primary and secondary recognition sites for substrates and inhibitors. The modulative effect exerted by aluminum on the enzyme hydrolytic activity has been investigated also as a function of pH. The ion-linked effect appears to be dependent on the pH in a complex fashion, which suggests that aluminum binding is controlled by the protonation of at least two classes of residues on the enzyme molecule.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s007750050138
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