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Appl. Environ. Microbiol., 12 1997, 4807-4811, Vol 63, No. 12
M Politino, SM Tonzi, WV Burnett, G Romancik and JJ Usher
A novel cephalosporin esterase (EC 3.1.1.41) from Rhodosporidium toruloides
was purified to gel electrophoretic homogeneity. The enzyme is a
glycoprotein with a molecular mass of 80 kDa. Upon deglycosylation, several
forms of the enzyme were observed with a molecular mass range between 60
and 66 kDa. The isoelectric point of the enzyme is approximately 5.6, with
the pH optimum for activity occurring at 6.0. The optimal activity of the
enzyme occurred at 25 degrees C, with the enzyme rapidly losing activity at
temperatures above 25 degrees C. The enzyme deacetylated a variety of
cephalosporin derivatives, including cephalosporin C; the Km for this
substrate is 51.8 mM, and the Vmax is 7.9 mumol/min/mg. In addition to
cephalosporins, the enzyme hydrolyzed short-chain p-nitrophenyl esters,
with the activity decreasing with increasing ester chain length. The enzyme
also has the ability to acetylate desacetyl cephalosporins in high yields
under mild conditions in the presence of various acetyl donors. A
comparison of the physical properties of the esterase with those of other
well-characterized cephalosporin esterases indicates that the enzyme is
unique in this class.
Copyright © 1997, American Society for Microbiology
Purification and characterization of a cephalosporin esterase from Rhodosporidium toruloides
Department of Enzyme Development, Bristol-Myers Squibb Company, Syracuse, New York 13221-4755, USA. mpolitin@usccmail.uscc.bms.com
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