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The Function of the Two Subunits of Thermophilic Aminopeptidase I

E Stoll, L H Ericsson, H Zuber

Proc Natl Acad Sci U S A. 1973 Dec;70(12):3781-4.

PMID: 4521203

Abstract:

The thermophilic high-molecular-weight aminopeptidase I (EC 3.4.11.1) from Bacillus stearothermophilus is composed of 12 subunits of two different types (alpha,beta) which can combine in various ratios. Only one type of subunit (alpha) is needed for the degradation of neutral peptides, but dipeptides having amino-terminal aspartic or gultamic acid are substantially hydrolyzed only by enzyme containing the other subunit (beta) as well. Asp-Gly inhibits the enzymatic hydrolysis of glutamic acid 1-(4-nitroanilide) very strongly but hardly affects the hydrolysis of leucine p-nitroanilide. These results indicate that both types of subunit have hydrolytic activity but different specificity. The two subunits have identical molecular weights and their amino-terminal regions are homologous, suggesting that the two chains originate from a single ancestral gene by gene duplication and independent mutation.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP24032357 L-Glutamic acid 1-(4-nitroanilide) L-Glutamic acid 1-(4-nitroanilide) 24032-35-7 Price
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