Ca/sup 2 +/-dependent proteolytic activity in crab claw muscle: effects of inhibitors and specificity for myofibrillar proteins
The claw closer muscle of the Bermuda land crab, Gecarcinus lateralis, undergoes a sequential atrophy and restoration during each molting cycle. The role of Ca/sup 2 +/-dependent proteinases in the turn-over of myofibrillar protein in normal anecdysial (intermolt) claw muscle is described. Crab Ca/sup 2 +/-dependent proteinase degrades the myofibrillar proteins actin, myosin heavy and light chains, paramyosin, tropomyosin, and troponin-T and -I. Ca/sup 2 +/-dependent proteinase activity in whole homogenates and 90,000 x g supernatant fractions from muscle homogenates has been characterized with respect to Ca/sup 2 +/ requirement, substrate specificity, and effects of proteinase inhibitors. The enzyme is inhibited by antipain, leupeptin, E-64, and iodoacetamide; it is insensitive to pepstatin A. The specificity of crab Ca/sup 2 +/-dependent proteinase was examined with native myosin with normal ATPase activity as well as with radioiodinated myosin and radioiodinated hemolymph proteins. Hydrolysis of /sup 125/I-myosin occurs in two phases, both Ca/sup 2 +/-dependent: (1) heavy chain (M/sub r/ = 200,000) is cleaved into four large fragments (M/sub r/ = 160,000, 110,000, 73,000, 60,000) and numerous smaller fragments; light chain (M/sub r/ = 18,000) is cleaved to a 15,000-Da fragment; (2) the fragments produced in the first phase are hydrolyzed to acid-soluble material. Although radioiodinated native hemolymph proteins are not susceptible to the Ca/sup 2 +/-dependent proteinase, those denatured by carboxymethylation are degraded. These data suggest that crab Ca/sup 2 +/-dependent proteinase is involved in turnover of myofibrillar protein in normal muscle and muscle undergoing proecdysial atrophy.
- Research Organization:
- Oak Ridge National Lab., TN
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 6472580
- Journal Information:
- J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 258:17; ISSN JBCHA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH METALS
ANIMAL TISSUES
ANIMALS
AQUATIC ORGANISMS
ARTHROPODS
BETA DECAY RADIOISOTOPES
BODY
CALCIUM
CHEMICAL REACTIONS
CRABS
CRUSTACEANS
DAYS LIVING RADIOISOTOPES
DECAPODS
DECOMPOSITION
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
ENZYME ACTIVITY
ENZYME INHIBITORS
ENZYMES
HYDROLYSIS
INTERMEDIATE MASS NUCLEI
INVERTEBRATES
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLING
LYSIS
METALS
MOLTING
MUSCLES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PROTEINS
RADIOISOTOPES
RESPONSE MODIFYING FACTORS
SOLVOLYSIS
TISSUES
TRACER TECHNIQUES