ΜΕΛΕΤΗ ΤΟΥ ΣΥΣΤΗΜΑΤΟΣ ΚΑΛΠΑΙΝΗΣ-ΚΑΛΠΑΣΤΑΤΙΝΗΣ ΑΠΟ ΤΟ ΜΥ ΤΟΥ ΒΡΑΧΙΟΝΑ ΤΟΥ ΧΤΑΠΟΔΙΟΥ OCTOPUS VULGARIS

Abstract

INITIALLY, THE CALPAIN AND CALPASTATIN WERE PURIFIED. CALPAIN IS A HOMOPOLYMER WITH A MOLECULAR WEGHT OF 520 KDA AND EACH SUBUNIT HAS A MOLECULAR WEIGHT OF 65KDA. IT IS SHOWN TO BE AN INTRACELLULAR, NEUTRAL, CYSTEINE, CA^2-DEPENDENT PROTEINASE WHICH BELONG S TO THE CATEGORY OF M-CALPAINS AND WHICH IS INHIBITED BY CALPASTATIN REVERSIBLY. CALPAIN IS AUTOLYSED IN THE PRESENCE OF CA^2 AND IN THE ABSENCE OF SUBSTATE, UNDER SIMILAR OPTIMUM CONDITIONS TO THOSE OF ENZYME ACTIVITY. CALPAIN PROTEOLYSES MYOSIN, PARAMYO SIN AND ACTIN OF INTACT MYOFIBRILS, WHILE FROM THE PURIFIED MYOFIBRILAC PROTEINS PROTEOLYSES MYOSIN, Β-AND Γ-PARAMYOSIN, BUT NOT A-PARAMYOSIN AND G-ACTIN. THE RESULTS OF THIS THESIS INDICATE THAT THE WAY OF CALPAIN'S ACTION MUST BE QUITE COMPLICATED AND T HAT THIS ENZYME IS PROBABLY INVOLVED IN EXTREMELY SPECIFIC AND STRICTLY CONTROLED PATHWAYS OF PROTEOLYTIC MODIFICATION AND NOT IN A NON SPECIFIC, GENERALPROTEOLYSIS.