BIOSYNTHESIS OF LEUPEPTIN .2. PURIFICATION AND PROPERTIES OF LEUPEPTIN ACID SYNTHETASE

An enzyme which condenses acetyl-L-leucyl-L-leucine and l-arginine into acetyl-l-leucyl-L-leucyl-l-arginine (leupeptin acid) was partially purified from a cell extract of Streptomyces roseus MA839-Al. With respect to this catalytic activity, the enzyme showed the following characteristics: ATP is essential; optimum pH is 9.5; the activity is inhibited either by EDTA or pyrophosphate or N-ethylmaleimide. The molecular weight of the enzyme is about 260,000 daltons. It also catalyzes some other extension reactions, such as, acetyl-L-leucine+ l-leucine+l-arginine→leupeptin acid, and acetyl-l-leucine+L-leucine → acetyl-L-leucyl-l-leucine, but neither L-leucine+l-arginine -» (l-leucyl)i_2-l-arginine, nor acetyl-l-leucine+l-arginine acetyl-L-leucyl-L-arginine. ATP-PPi exchange, catalyzed by this enzyme, proceeds with either acetyl-L-leucine, or acetyl-L-leucyl-L-leucine or L-leucine, but not with acetate or arginine. © 1979, JAPAN ANTIBIOTICS RESEARCH ASSOCIATION. All rights reserved.