The relationship between biological activity and primary structure of troponin I from white skeletal muscle of the rabbit.
1. A series of defined peptides which span the complete sequence were produced from troponin I isolated from white skeletal muscle of the rabbit. 2. Two peptides, CF1 (residues 64-133) and CN4 (residues 96-117) inhibited the Mg2+-stimulated adenosine triphosphatase of desensitized actomyosin. This inhibition was potentiated by tropomyosin and the Mg2+-stimulated adenosine triphosphatase of desensitized actomyosin. This inhibition, unlike that of troponin I and peptides derived from it, was not potentiated by tropomyosin. 4. The most active inhibitor, peptide CN4, was 45-75% as effective as troponin I when compared on a molar basis. The inhibitory peptide, CN4, and also whole troponin I were shown by affinity chromatography to interact specifically with actin. 5. A strong interaction with troponin C was demonstrated with peptide CF2 (residues 1-47), from the N-terminal region of troponin I. Somewhat weaker interactions were shown with peptides CN5 (residues 1-21) and with the inhibitory peptide CN4. 6. The significance of these interactions for the mechanisms of action of troponin I is discussed.
D000199:Actins; D000205:Actomyosin; D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D000595:Amino Acid Sequence; D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D002846:Chromatography, Affinity; D003574:Cytochrome c Group / Q000494:pharmacology; D008274:Magnesium; D009113:Muramidase / Q000494:pharmacology; D009124:Muscle Proteins / Q000378:metabolism; D009132:Muscles / Q000032:analysis*; D010455:Peptides / Q000302:isolation & purification; D011817:Rabbits; D012473:Salmine / Q000494:pharmacology; D014335:Tropomyosin / Q000494:pharmacology; D014336:Troponin / Q000378:metabolism; D014357:Trypsin
D000199:Actins; D003574:Cytochrome c Group; D009124:Muscle Proteins; D010455:Peptides; D014335:Tropomyosin; D014336:Troponin; D000205:Actomyosin; D012473:Salmine; D009113:Muramidase; D014357:Trypsin; D000251:Adenosine Triphosphatases; D008274:Magnesium