Biomaterial Database

Cross-linking studies related to the location of the rigor compliance in glycerinated rabbit psoas fibers: is the SII portion of the cross-bridge compliant? 1984

K Tawada, and M Kimura

The muscle tension generation model of Huxley and Simmons (1971) postulates an independent elastic element in the cross-bridge. This elastic structure was tentatively placed in the SII portion of the cross-bridge in the model. To check this assumption, we fixed the SII portion onto the surface of the thick filament in glycerinated rabbit psoas fibers in rigor by chemically cross-linking with dimethyl suberimidate, and compared the stiffness of the cross-linked fibers with that of the fibers before cross-linking. The stiffness was determined by measuring the tension increment upon stretching a fiber segment in rigor. The contribution of the end compliance was found to be small. Cross-linking increased the rigor stiffness by 20 to 30%. Almost the same amount of the stiffness increase was also observed at a sarcomere length where there was no overlap between the thin and thick filaments, and in a fiber segment cross-linked in relaxing solution. Therefore, the 20 to 30% increase of the stiffness is not caused by the fixation of the SII portion onto the thick filament but caused by the cross-linking of some parallel elastic components. Since the rigor stiffness before cross-linking is almost proportional to the overlap between thick and thin filaments, we conclude that the muscle stiffness in rigor does not originate in the SII portion but reflects some compliance of the head portion of the cross-bridge.

UI	MeSH Term	Description	Entries
D007096	Imidoesters	Esters of the hypothetical imidic acids. They react with amines or amino acids to form amidines and are therefore used to modify protein structures and as cross-linking agents.	Imidates
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D009126	Muscle Relaxation	That phase of a muscle twitch during which a muscle returns to a resting position.	Muscle Relaxations,Relaxation, Muscle,Relaxations, Muscle
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D009210	Myofibrils	The long cylindrical contractile organelles of STRIATED MUSCLE cells composed of ACTIN FILAMENTS; MYOSIN filaments; and other proteins organized in arrays of repeating units called SARCOMERES .	Myofilaments,Myofibril,Myofilament
D009218	Myosins	A diverse superfamily of proteins that function as translocating proteins. They share the common characteristics of being able to bind ACTINS and hydrolyze MgATP. Myosins generally consist of heavy chains which are involved in locomotion, and light chains which are involved in regulation. Within the structure of myosin heavy chain are three domains: the head, the neck and the tail. The head region of the heavy chain contains the actin binding domain and MgATPase domain which provides energy for locomotion. The neck region is involved in binding the light-chains. The tail region provides the anchoring point that maintains the position of the heavy chain. The superfamily of myosins is organized into structural classes based upon the type and arrangement of the subunits they contain.	Myosin ATPase,ATPase, Actin-Activated,ATPase, Actomyosin,ATPase, Myosin,Actin-Activated ATPase,Actomyosin ATPase,Actomyosin Adenosinetriphosphatase,Adenosine Triphosphatase, Myosin,Adenosinetriphosphatase, Actomyosin,Adenosinetriphosphatase, Myosin,Myosin,Myosin Adenosinetriphosphatase,ATPase, Actin Activated,Actin Activated ATPase,Myosin Adenosine Triphosphatase
D010446	Peptide Fragments	Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.	Peptide Fragment,Fragment, Peptide,Fragments, Peptide
D011817	Rabbits	A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes.	Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
D004120	Dimethyl Suberimidate	The methyl imidoester of suberic acid used to produce cross links in proteins. Each end of the imidoester will react with an amino group in the protein molecule to form an amidine.	Bismethyl Suberimidate,Dimethylsuberimidate,Suberimidate, Bismethyl,Suberimidate, Dimethyl
D004548	Elasticity	Resistance and recovery from distortion of shape.