Purification and characterization of two metalloproteinases from squid mantle muscle, myosinase I and myosinase II.
Metalloproteinases, myosinase I and myosinase II, that hydrolyze the heavy chain of myosin, were purified from squid mantle muscle. Myosinase I does not hydrolyze other muscle proteins, casein, haemoglobin, or MCA-substrates, while II hydrolyzes tropomyosin. Both myosinase I and myosinase II gave a single protein band on SDS-PAGE with a molecular mass of 16 and 20 kDa, respectively. Their activities were inhibited by EDTA and 1,10-phenanthroline, and II was also inhibited by EGTA. They could be reactivated with some divalent cations, I was especially reactivated with Co2+ and II especially with Zn2+. The optimum pH of both activities was 7.0; the optimum temperature for both was 40 degrees C. Myosinase I hydrolyzes myosin heavy chains to produce 130 and 90 kDa fragments. The N-terminal amino-acid sequence of the 90 kDa fragment indicates that myosinase I splits the myosin heavy chain between Ala-1161 and Thr-1162 in subfragment 2. Myosinase II hydrolyzes myosin heavy chain to produce 158 and 65 kDa fragments, and it splits between Glu-1381 and Thr-1382 in LMM. Myosinases I and II are most likely related to the metabolism of myosin in vivo.
Okamoto
Y
Y
Department of Chemistry, Faculty of Science and Technology, Sophia University, Tokyo, Japan.
Otsuka-Fuchino
H
H
Horiuchi
S
S
Tamiya
T
T
Matsumoto
J J
JJ
Tsuchiya
T
T
D000595:Amino Acid Sequence; D000818:Animals; D002413:Cations, Divalent; D002645:Chickens; D049832:Decapodiformes / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D008666:Metalloendopeptidases / Q000737:chemistry / Q000302:isolation & purification*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009132:Muscles / Q000201:enzymology*; D009218:Myosins / Q000378:metabolism; D011817:Rabbits; D013379:Substrate Specificity; D013696:Temperature
D002413:Cations, Divalent; D008666:Metalloendopeptidases; C079297:myosinase I; C079298:myosinase II; D009218:Myosins