J. Biol. Chem., Vol. 265, Issue 10, 5809-5815, 04, 1990
Purification of a novel type of calcium-activated neutral protease from rat brain. Possible involvement in production of the neuropeptide kyotorphin from calpastatin fragments
Y Yoshihara, H Ueda, N Fujii, A Shide, H Yajima and M Satoh
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kyoto University, Japan.
We have found a novel type of Ca2(+)-activated neutral protease in rat
brain cytosol which cleaves -Tyr-Arg-containing calpastatin fragments to
release the neuropeptide kyotorphin. This enzyme was purified about
26,000-fold by column chromatography as follows: DE52 cellulose, Ultrogel
AcA 44, thiopropyl-Sepharose 6B, second DE52 cellulose, Ultrogel AcA 34,
and blue Sepharose CL-6B. The molecular mass of the enzyme was estimated to
be 65-75 kDa by gel filtration. The purified enzyme gave a single band of
74 kDa by sodium dodecyl sulfate- polyacrylamide gel electrophoresis. Some
properties of this enzyme were similar to those of the calpains, i.e. an
absolute requirement for Ca2+, maximal activity at neutral pH, and
inhibition by sulfhydryl reagents such as p-chloromercuriphenylsulfonic
acid and N- ethylmaleimide. However, it differs from the calpains in that
it possesses no caseinolytic activity, separates from the calpains on the
first DE52 column, and is insensitive to leupeptin and E-64 (N-[N-(L-3-
trans-carboxyoxrian-2-carbonyl)-L-leucyl]agmatine). Thus, the molecular
mass, the substrate specificity, the chromatographic behavior, and the
inhibitor spectrum all suggest that this enzyme is a novel type of
Ca2(+)-activated neutral protease.